Over the weekend, Doctor Who celebrated its 50th anniversary with a special episode simultaneously released in over 80 countries around the world. The special, which united Tenth Doctor David Tennant with current Eleventh Doctor Matt Smith, was jam-packed with so many references to earlier episodes that even long-time Who fans may not have caught them all. Want to see what you missed? Here's a guide to the many references and easter eggs in "The Day of the Doctor," annotated by Doctor Who: A History author Alan Kistler.

What We See: A policeman passes by a sign for I.M Foreman, scrap merchant, located at 76 Totter's Lane in Shoredritch, Long. The policeman then passes by Coal Hill Secondary School, where "W. Coburn" is listed as headmaster

Links to the Past: This opening image echoes the very first episode of Doctor Who, "An Unearthly Child," which began with a policeman walking past I.M. Foreman's scrap yard, which housed the TARDIS. The scene then shifted to Coal Hill Secondary School, where teachers Ian Chesterton and Barbara Wright discussed their pupil Susan. Susan turned out to be the Doctor's granddaughter and Ian and Barbara became the first human passengers of the TARDIS; a friend of Susan's named Wendy Coburn appeared in the 2001 novella "Time and Relative."

What We See: In her classroom, Clara – who is now a teacher – writes, "Waste no more time arguing about what a good man should be. Be one.

Links to the Past: This is a quote from Marcus Aurelius that not only describes the theme of the special, but references an earlier remark by the Eleventh Doctor that he no longer considered himself a good man.

What We See: Clara drives away from Coal Hill School at 5:16 pm.

Links to the Past: 5:16 pm is the exact time that Doctor Who first premiered on November 23, 1963. Many sources claim it aired at 5:15 pm, but the broadcast was delayed by one minute and twenty seconds due to the earlier show Grandstand running long.

What We See: Kate Lethbridge-Stewart, head of UNIT, orders the TARDIS brought to her.

Links to the Past: Kate is the daughter of the late/retired brigadier Sir Alistair Gordon Lethbridge-Stewart, who first met the Doctor in "The Web of Fear" (1968) and was a founder of UNIT. Despite often arguing with the man, the Brigadier became one of the Doctor's best friends, teaming up with his many different incarnations over the years. He even once went to Gallifrey and punched the Master in the face. The Eleventh Doctor learned of his passing in "The Wedding of River Song" (2011).

What We See: Kate Lethbridge-Stewart is assisted by a young UNIT agent named Osgood. She wears a long, colorful scarf that the Eleventh Doctor compliments.

Links to the Past: Osgood may be related to Tom Osgood, a UNIT soldier seen in "The Daemons" (1971). Her scarf is a copy of one of the many worn by the Fourth Doctor; it's even possible this is one of his discarded scarves. It also foreshadows the appearance of the Curator.

What We See: Entering the museum, the Doctor tells Clara he works for the governmental agency UNIT.

Links to the Past: When the Third Doctor was exiled to Earth for a few years, unable to travel through time and space, he became UNIT's scientific advisor "Dr. John Smith" and resided in the lab. After regaining his freedom and then regenerating into the Fourth Doctor, he decided he didn't like feeling tied down to a job and left, though he never officially quit. In "Aliens in London" (2005), viewers learned that the UNIT alarm for a Doctor sighting is "Code 9."

Clara and the Doctor encounter the Gallifreyan painting.

What We See: A 3-D Gallifreyan painting created by capturing a sliver of time.

Links to the Past: The Doctor and his companion Romana discussed Time Lords creating paintings with technology in the 1979 story "City of Death." The painting features Arcadia, revealed here to be Gallifrey's "second city." Arcadia is also the name of a planet later visited by Amy and the Doctor in "Vincent and the Doctor." In the 2006 episode "Doomsday," the Tenth Doctor said he survived the Time War partly "by fighting on the front lines" and that he witnessed "the fall of Arcadia.""

What We See: In Arcadia, we see the War Doctor (John Hurt), the incarnation of our hero who fought in the Last Great Time War.

Links to the Past: In the 35th anniversary novel The Infinity Doctors, we learned there were two other great Time Wars before the First Doctor left Gallifrey. During the final war, the Eighth Doctor decided he was the only one could stop it and took a regeneration potion that programmed his next incarnation to be a warrior. This, along with his refusal to call himself the Doctor, means Hurt's incarnation isn't counted as part of the basic numbering system for the various Doctors. Christopher Eccleston's version is thus still the Ninth Doctor, even though he was the hero's tenth incarnation.

What We See: The War Doctor declares "No more," one of the titles of the Arcadia painting.

Links to the Past: This phrase was also uttered by Rassilon, the first Time Lord, when he intended to execute the Master and destroy reality in "The End of Time."

What We See: The War Room of Gallifrey, where a Time Lord General is told that the High Council has called an emergency session to make "plans of their own."

Links to the Past: This High Council session mentioned was depicted in "The End of Time," when Rassilon and the High Council created a link to transport themselves – and Gallifrey – to Earth. But the Tenth Doctor severed the link, returning the High Council and Gallifrey to the Time War at the instant they had left. The Time Lords also wear new costumes that harken back to designs seen in classic Doctor Who, while the soldiers have the Seal of the Time Lords (also known as the Seal of Rassilon) decorating their armor.

What We See: The Moment's interface avatar adopts the form of Rose Tyler, first companion of the modern-day Doctor Who.

Links to the Past: The Moment chooses Rose's form because she was a friend of the Doctor, but then realizes they haven't met yet. Similarly, the TARDIS had trouble distinguishing between the future, present and past when it temporarily took human form in "The Doctor's Wife." The Moment's interface also adopts Rose's physical nature from "The Parting of the Ways," when she accessed the power of the space-time vortex and became the god-like force called Bad Wolf. This power allows the Moment to breach the time locks that seal the Last Great Time War from interference.

What We See: The Moment judges those who use its power, and so decrees that if the Doctor uses it to wipe out all Daleks and Time Lords, he will be forced to survive to live with the consequences.

Links to the Past: In the 2005 episode "Dalek," the Doctor first admitted that he had been the one to end the Time War by wiping out both sides. He later added that his survival was not achieved by his own choice. This is the first time we learn what he meant.

What We See: In 1562, the Tenth Doctor rides out of the TARDIS on a horse, with Elizabeth I alongside him.

Links to the Past: Elizabeth I has appeared many times in the Whoniverse. In the 2007 episode "The Shakespeare Code," the Tenth Doctor runs into Elizabeth I in 1599 and is surprised when she orders her guards to kill him. This special finally reveals that thirty-seven years earlier, he married her – and then immediately ditched her. The marriage was mentioned in "The End of Time" and "Amy's Choice."

Photo: Ariel Zambelich/WIRED Queen Elizabeth I's horse turns into a Zygon.

What We See: The Tenth Doctor's horse is really a creepy, shape-shifting Zygon.

Links to the Past: The Zygons debuted in 1975's "Terror of the Zygons," which featured the Brigadier, Sarah Jane Smith and the Loch Ness Monster. This is the first time since then that they've fought the Doctor on-screen, though they've appeared several times in tie-in media. David Tennant has said that the Zygons were his favorite monsters of classic Doctor Who.

What We See: The Tenth Doctor tells the lop-eared rabbit that he's 904 years old.

Links to the Past: According to his own timeline, this Tenth Doctor is currently in between the TV specials "The Waters of Mars" and "The End of Time," just over two years before he regenerates.

What We See: The Eleventh Doctor wanders past several statues underneath cloth coverings, curious about the dust and sand on the floor.

Links to the Past: According to Peter Davison's comedy special "The Five Doctors(ish) Reboot," those aren't statues but former Doctors Colin Baker, Sylvester McCoy and Davison himself.

What We See: Kate realizes multiple Doctors are meeting and asks Malcolm for the "Cromer" report. She says it will be in the 1970s or 1980s archives, "depending on the data protocol."

Links to the Past: In "The Three Doctors," the Doctors and UNIT's UK base were temporarily transported to an anti-matter reality. Unable to comprehend such an event, Brigadier Lethbridge-Stewart instead concluded that the base had been teleported to the town of Cromer in Norfolk. Malcolm" is likely Dr. Malcolm Taylor, seen in "Planet of the Dead" (2009). Kate's remark about the data protocol is a reference to what some Whovians call the "UNIT Dating Controversy," which involves two conflicting dates for the formation of UNIT.

What We See: The Eleventh Doctor tries to scare Elizabeth I's guards by referring to Clara as the Wicked Witch of the Well. The Tenth and Eleventh Doctors try to reverse the polarity of the time tunnel.

Links to the Past: The Doctor's comment is a reference to the Witch of the Well, a character in the 2013 episode "Hide." The Third Doctor also had such a habit of solving problems by "reversing polarity", a phrase he used so commonly that it became ongoing joke in the mythos.

What We See: The War Doctor criticizes both the Tenth and Eleventh Doctors.

Links to the Past: These criticisms echo complaints made by some classic era fans who don't care for the modern era of the show.

What We See: Kate Stewart shows Clara the Black Archive, first seen in The Sarah Jane Adventures (and apparently relocated to the Tower of London).

Links to the Past: There are numerous artifacts from previous Doctor Who stories here: River Song's red heels from "The Time of Angels"; the casing of the Supreme Dalek from "The Stolen Earth" and "Journey's End"; the magnetic clamps Torchwood 1 possessed in "The Army of Ghosts" and "Doomsday"; the gun Rose Tyler used in "The Stolen Earth"; a modern era Cyberman head; a facemask of one of the clockwork robots from "The Girl in the Fireplace"; a Dalek machine gun from "Daleks in Manhattan"; Amy Pond's pinwheel from "The Eleventh Hour"; the sonic probe used by an older version of Amy in "The Girl Who Waited"; and Jack Harkness's vortex manipulator, which allows limited travel through the space-time vortex. In Doctor Who comics published by IDW, the Tenth Doctor sent Martha Jones to the Black Archive, saying he had aided in its creation during his third life. That would explain why he knows of its existence, despite Kate's belief to the contrary.

The easter egg shelves of the Black Archive

What We See: Clara looks over a blackboard covered with photos and files on the Doctor's friends and companions from the modern and classic programs.

Links to the Past: One photo depicts Rose Tyler in a scene from the 2008 episode "Turn Left" – a scene that took place in an alternate timeline that was erased. When she later examines the photos, Clara focuses on the Doctor's granddaughter Susan, who joined him when he first escaped Gallifrey in a stolen TARDIS.

What We See: The access code to Jack Harkness's vortex manipulator is 1716231163.

Links to the Past: This is code for 17:16 (or 5:16 pm), the 23rd of November, 1963 – again, the exact date and time that Doctor Who debuted on television.

What We See: At the Queen's private wedding, the War Doctor asks if his future incarnations kiss often.

Links to the Past: Before the modern show, the Eighth Doctor was the only incarnation to ever kiss anyone on-screen. Although some viewers disliked the kiss and the idea of making the Doctor a romantic figure of any kind, Russell T. Davies enjoyed this new take. During the modern era of Doctor Who, each Doctor has kissed their regular companions (and sometimes other folks, too).

What We See: The TARDIS adopts the walls of its original interior from 1963 and then shifts into the Eleventh's control room. The Tenth Doctor examines it with delight before frowning and saying, "I don't like it."

Links to the Past: This is an ongoing gag that started when the Second Doctor criticized the Third's TARDIS in "The Three Doctors," and later made the same comment when he saw the redecorated UNIT headquarters in "The Five Doctors." Hence the Eleventh Doctor's response, "You never do."

What We See: The Doctor contacts the Black Archive via a space-time telegraph he gave to Alistair Gordon Lethbridge-Stewart.

Links to the Past: This telegraph was first mentioned in "Terror of the Zygons" and was the first time in the mythos that the Doctor left a friend a means to contact him. Since then, he's occasionally given some people, like UNIT, a special TARDIS phone number.

What We See: The Doctors figure out a way to save Gallifrey while not changing history, since it will still be removed from the universe and appear to have been destroyed.

Links to the Past: This idea is similar to how the Doctor avoided his own death in "The Wedding of River Song," where he used trickery to make the event look as if it happened. Here, sending the planet to a pocket universe allows them to keep the timeline intact.

What We See: No doubt with help from the Moment, the Doctors summon all their other selves to save Gallifrey.

Links to the Past: The previous Doctors appear on the War Council's monitors thanks to archive footage. Their dialogue is likewise taken from archive footage, except for the First Doctor's lines, which were spoken by voice actor John Guilor. Interestingly, we see two different versions of the Seventh Doctor, one from when he appeared in the classic program and one from when he was much older and soon to regenerate in the 1996 TV-movie.

What We See: A mysterious Doctor joins the effort to save Gallifrey, and it is announced that "all thirteen" incarnations of the hero are now present.

Links to the Past (and Future): This is Peter Capaldi, who is set to make his official debut as the Twelfth Doctor on Christmas Day. In various stories of the classic Doctor Who program, it was stated that Time Lords have a limit of thirteen lives.

What We See: Left alone with the Gallifreryan painting, the Eleventh Doctor muses that one day he might like to retire and become a curator of this very museum. The Curator remarks that the Doctor might just do this one day, and the hero is surprised to see that the white-haired man has the same face as one of his previous incarnations.

Links to the Past: The Curator is portrayed by Tom Baker, who played the Fourth Doctor from 1974-1981 and remains one of the most popular incarnations. He implies he is a future version of the Doctor who retires to look over a museum. The BBC Books e-book Summer Falls, an in-universe book written by Amelia Williams (aka Amy Pond), also featured a character known only as the Curator, who resembles the Eleventh Doctor.

What We See: After learning that the plan worked and the Time Lords are alive, the Eleventh Doctor asks if it's his destiny to find Gallifrey now. The Curator says that this is his choice.

Links to the Past: Many of Steven Moffat's stories have addressed that "time can be rewritten" and that there is no fate. he Eleventh Doctor is free to choose his own path. A new era begins as the Doctor sets out to find his lost home world Gallifrey; it's a direct inversion of the original Doctor Who program, which began with him desperately running away from it.