Deliberate "mistake": In the shot near the end of the film where Donnie grabs the keys for the station wagon, you can see a Blockbuster Video member card in a cup. That card design wasn't used until the mid to late 1990's. This movie is set in 1988. Deliberate as it's a product placement, but still wrong.

Visible crew/equipment: When Donnie and his Dad are in the car, talking, prior to nearly hitting Grandma Death, in the window behind Donnie's Dad is the reflection of a vehicle which says "Darko" clearly on it.

Continuity: When Cherita makes her mark on the lifeline blackboard, there are some smudges on the broad chalk line. In the next shot, the line is perfect again.

Continuity: At the bus stop when Donnie says to his sister that he'll throw her doll in the garbage disposal, watch the red-headed girl next to her. The girl positions her head differently each shot. From the front, she's looking at Donnie, and behind she's looking at his sister.

Deliberate "mistake": During the "Sparke Motion" dance scene, the dance instructor is mouthing the wrong words to the song the girls are dancing to. "West End Girls" by the Pet Shop Boys was originally going to be the dance number, and that is actually the song playing for the recording of the scene. Richard Kelly couldn't get permission to use it, and "Notorious" by Duran Duran was substituted. The teacher is plainly mouthing words form the wrong song.

Continuity: In the class with the Lifeline exercises, the "L" on the word "LOVE" changes how it is drawn about 4 or 5 times between shots.

Continuity: At the bus stop, Donnie's little sister changes positions between shots. From behind, she's in front of the red headed girl and in the frontal shot she's standing right next to her.

Continuity: Whilst Donnie talks about Graham Greene's book, Gretchen walks into the class. Watch Donnie's hands on his desk. Between shots when she enters the class, his hands change position majorly.

Continuity: In the scene near the beginning in which Donnie's dad is using the leaf blower, the trees are covered with very green leaves while the ground is covered in very colorful ones. There are no naked trees anywhere or trees with leaves that have changed, and, when considering the amount of leaves on the ground, there should be many.

Continuity: In the class with the Lifeline exercises, Cherita writes an 'X' on the board. In the next shot, the letter is fainter and less distinct.

Continuity: In the scene where the students are asked to write "They made me do it" on the blackboard, Sam Bylan is called up just before Donnie, yet on the principal's checklist Cherita is before Donnie and after Sam. (Despite any deleted shots, this is still a mistake in the theatrical release.)

Audio problem: In the first dinner scene, look closely at the way Eddie Darko's mouth moves as he laughs after the "What's a f***ass?" question from Samantha. He takes a bite of his pizza, and his mouth movements do not match the sound of his laughter.

Other: Cherita has a speech impediment: instead of saying "shut up" she says "chut up." This is also reflected in the subtitles every time it happens EXCEPT at the bus stop, when it reads "shut up."

Continuity: In the scene where Donnie Darko and his sister are having a Halloween party, Donnie takes his girlfriend Gretchen upstairs while the song 'Love Will Tear Us Apart' by Joy Division is played. Watch closely as they ascend the stairs and keep an ear on the song as well. Somehow they manage to get all the way from the top of the stairs, to being sat down comfortably on a bed in someone's bedroom (with the door closed) without the audience hearing any interruption or 'jump' in the song whatsoever. This means they must have traversed the landing, entered the room and got properly sat down on the bed together in precisely no time at all. Quite a fitting mistake considering the movie's time travel theme.