Background actors, also known as extras, have one of the most important jobs on a film shoot. They contribute to the overall believability of a scene while making it easier for filmmakers to control a set or location. But sometimes, extras draw attention to themselves—either intentionally or unintentionally—and break the main focus of the scene.

1. Star Wars

When Luke Skywalker, Han Solo, Princess Leia, and Chewbacca are trapped in one of the trash compacters on the Death Star, a group of Stormtroopers manage to unseal a blast door to find C-3PO and R2-D2 in a control room. As the Stormtroopers enter, one of them hits his head on the blast door. While this was considered a blink-and-you'll-miss-it moment from the original Star Wars, George Lucas added a "thud" sound effect in its special edition to highlight the gaffe.

2. Back to the Future Part III

At the very end of Back to the Future Part III, Doc Brown shows up in Hill Valley 1985 in a brand new time machine made from the locomotive he used to help Marty get back to the future. When Doc is introducing his new family to Marty and Jennifer, you can clearly see Doc's youngest son Verne, played by Dannel Evans, gesturing for help and then pointing to his groin. It appears that the very young Evans needed to go to the bathroom, but didn't want to stop the take.

3. North By Northwest

Before the iconic chase scene on Mount Rushmore, Eve Kendall "shoots" Roger Thornhill in the National Park's cafeteria. After multiple and noisy takes, you can see a little boy in the background anticipate the shot and plug his ears before she fires the gun.

4. Willy Wonka and the Chocolate Factory

During the "Candy Man" song, one of the little girls almost gets smacked in the jaw when the creepy candy store clerk lifts the hatch to let the children behind the counter. Fortunately, the little girl has ninja-like reflexes to divert injury.

5. Ghostbusters

Just before the Ghostbusters battle Gozer the Gozerian, they greet cheering fans just outside of Dana Barrett's Central Park West apartment building. One of the fans is an overly-enthusiastic businessman who screams, "Ghostbusters, alright!," as he draws attention to himself and away from the Ghostbusters.

6. Quantum of Solace

In Quantum of Solace, James Bond is at a pier and behind him is an extra who appears to be sweeping air with a broom that is not touching the pavement.

7. The Dark Knight Rises

While Batman and Catwoman are on a rooftop fighting Bane's goons, one of the henchmen poses in a fighting stance and then falls to the ground without getting hit.

8. Everything Must Go

Salesman Nick Halsey visits Delilah, one of his old high school classmates, to re-evaluate his life. She has two children now and their first appearance seems normal enough with the pair playing in the front yard. However, when the film cuts back to the children in the background, they appear to be frozen in place, while Nick and Delilah reminisce.

9. Coach Carter

When undefeated Richmond High School varsity basketball coach Ken Carter cancels the big game with Fremont because of his team's poor grades, the school's fan base gets extremely upset and vocal about his final decision. One extra was overly furious, as he proceeds to comically shake his fist and jeer at Coach Carter.

10. The Last Samurai

When Captain Nathan Algren returns to his Japanese camp, his horse kicks one of the Samurai extras in the crotch as Algren dismounts. The extra is clearly a professional, because he just lines up into formation until the end of the scene.

11. Teen Wolf

After the Beacon High School Beavers win the basketball game at the tail end of Teen Wolf, you can see an extra in the gym's bleachers expose her underwear. She starts to cover up her unzipped jeans with a red sweater, as the character Scott Howard hugs his dad. Once you notice this moment, you'll never watch Teen Wolf in the same way again.

12. Being John Malkovich

When John Malkovich spills onto the New Jersey Turnpike after being inside of his own head, he gets angry with Craig Schwartz for making a business out of his inner thoughts and experiences. After he threatens to sue Schwartz, an extra throws a beer can at Malkovich's head when he begins to walk away. According to Being John Malkovich director Spike Jones, this moment wasn't scripted and a drunken extra thought up the scenario after multiple long and boring takes.