The 40 Year Old Virgin - The hair removal scene was real, and so was Steve Carell's reaction.

Forrest Gump - Forrest's reply to Bubba, "My name's Forrest Gump. People call me Forrest Gump," was actually Hanks misspeaking, but it was left in the film.

The Burbs - Tom Hanks carrying the stretcher into the ambulance was made up on the spot.

Lock, Stock and Two Smoking Barrels - Nick the Greek breaking the glass table wasn't planned.

Full Metal Jacket - Sergeant Hartman yelling at his recruits was all improvised.

Scent of a Woman - Al Pacino falling over the trash can was unplanned.

Whiplash - Simmons actually slapped Teller.

American Beauty - Kevin Spacey throwing the plate against the wall was improvised.

The Revenant - Leonardo DiCaprio actually ate a slab of bison liver.

Eternal Sunshine of the Spotless Mind - Kate Winslet disappearing suddenly was unplanned and surprised Jim Carrey.

Lucky Number Slevin - Lucy Liu wasn't informed Josh Hartnett would be naked when she entered the room.

Alien - The cast had no prior knowledge about the chest burst scene.

The Other Guys - Will Farrel's response to Mark Wahlberg about a lion swimming was made up.

Mrs. Doubtfire - When the icing face mask started to melt, Robin Williams improvised all the jokes.

Harry Potter and the Goblet of Fire - Barty Crouch Junior imitating a snake's tongue was not in the script.

Scream - Mathew Lillard saying, "Ah... Houston, we have a problem," was ad libbed.

The Matrix - Keanu Reeves actually walked outside the building on the 34th floor.

Dirty Dancing - Patrick Swayze and Jennifer Grey crawling on the floor was not originally a part of the film.