Continuity: In the opening scene, on the floor there is a toy train on circular tracks when the monster sneaks in. When the monster trips backwards over the ball and skateboard then falls onto the jacks, the train and tracks are gone.

Continuity: At the beginning when you see the monster in the testing room from under the bed with the glowing eyes, you also see the soccer ball on the left side of the screen. This shot takes place on the side of the bed. After the monster gets scared, he backs up kicks the soccer ball, but it is now at the foot of the bed in the middle of the room.

Continuity: At the beginning of the film, we see Sully asleep in his bed and the alarm clock/radio on a bedside cabinet to the right. Later, when Boo climbs into Sully's bed, the clock/radio isn't there anymore.

Continuity: When Sully places the menu on the table he puts it face down (logo first), then when he lifts up the table, to quickly get Boo, the menu is face up.

Factual error: The map of the world on the scare floor shows Australia without Tasmania. This is best seen late in the movie after Boo has returned home, Sully is now management and when Mike asks him to follow him you can clearly see the world map behind Sully showing Australia and no Tasmania.

Trivia: Boo's real name is Mary, this is only just visible on one of the drawings she is making while in Mike and Sulley's apartment.