Netflix's glossy royal family drama "The Crown," now in its third season, turns viewers into amateur historians. (Who among us has not scurried off to Google in the middle of an episode, itching for factoids about Welsh nationalism and Labour Party politics?) The acclaimed series takes some liberties with the historical record, of course — but NBC News is here to help you separate fact from fiction. Be warned, though: spoilers ahead.

We'll begin with Queen Elizabeth II's only sibling: Princess Margaret, Countess of Snowdon (Helena Bonham Carter), who died in 2002. The second episode of the season, titled "Margaretology," centers on her 1965 tour of the United States, during which she is dispatched to dinner at the White House to try to convince President Lyndon B. Johnson (Clancy Brown) to bail out the British financial system. The show depicts the event as a loose, boozy affair featuring singing, dancing and the recitation of dirty limericks. But was the visit really such a swinging party? Let's go to the record.

Did Her Royal Highness bash JFK?

"Margaretology" depicts the princess breaking the ice with the American president by deriding his predecessor, President John F. Kennedy, who was assassinated just two years before the dinner. "I met him once," Margaret says coyly, sensing that her dining partner nurses a grudge against the slain leader. "I was left distinctly underwhelmed." The remark helps endear Margaret to Johnson, who proceeds to gratuitously mock the 35th president as a callow braggart.

Lord Snowdon, Mrs. "Lady Bird" Johnson, Princess Margaret and President Lyndon B. Johnson in 1965. RDB / ullstein bild via Getty Images

It is entirely possible that the real-life Margaret and Johnson insulted Kennedy in private, but a contemporaneous news report in The Los Angeles Times suggests it is highly unlikely they would bash him in front of other dignitaries and VIPs inside the White House State Dining Room.

The guest list, according to the newspaper, included Rose Kennedy, the slain president's mother; Joan Bennett Kennedy, the first wife of his brother, Massachusetts Sen. Ted Kennedy; and Texas Gov. John B. Connally, who was riding in the presidential limousine during the assassination. (Also invited: Hollywood star Kirk Douglas, opera singer Anna Moffo, and former President Dwight D. Eisenhower's son, John.)

Was the dinner such a wild shindig?

The episode depicts the meal leading to a spirited drinking contest ("Last man standing is the winner," Margaret says) and eventually a "limerick contest," during which Johnson, Margaret and her husband, photographer Tony Armstrong-Jones (Ben Daniels), recite a series of ribald, scatological rhyming verses that are not fit for publication on a family website. In a dryly comic touch, "Margaretology" includes a scene in which British Prime Minister Harold Wilson (Jason Watkins) relays the limericks back to Elizabeth II (Olivia Colman), who is not particularly amused.

The news reports from the time provide some clues that the dinner was not exactly stuffy or dull. "The party lasted longer than most White House affairs," The New York Times reported in its "Talk of Washington" column on Nov. 19, 1965. "Margaret and her husband did not leave until 1:35 this morning and the Johnsons, celebrating their 31st wedding anniversary, stayed on until the orchestra struck up 'Good Night Ladies' at 2 a.m."

The Los Angeles Times article about the dinner, for its part, says that Johnson offered a "lighthearted" champagne toast to the visiting couple, adding that the "sparkling dinner" was "followed by dancing in the East Room to music of Peter Duchin and his orchestra." The two couples boogied to the tune of "Everything's Coming Up Roses," according to the article.

But by and large, news coverage from the time does not indicate that the celebration was all that risqué or off-color, according to Carolyn Harris, a royal historian and author of "Raising Royalty: 1,000 Years of Royal Parenting," among other works about the monarchy.

"The coverage presents the dinner as comparatively uneventful, and the official dinner attracted less attention than the cost of the visit itself, especially since Margaret and Armstrong-Jones had reputations as jet-setters who socialized with the elite," Harris said in a recent phone interview.

"But that said, Margaret was known for her sense of humor and Johnson was known for occasionally making bawdy comments."