Continuity mistake: In the scene in the karaoke shop, watch the light through the window. Sometimes it's daylight outside, sometimes it's dark.
Continuity mistake: At the beginning "Pete" asks Violet for her autograph on a time card. She signs it and the "T" is not crossed, and when Pete puts it on the board it is crossed. Then at the end when Violet's dad buys it from Pete it is again not crossed. Also if you look at the "V" when she signs it and after Pete puts it up they are different. And lastly, when Violet signs her last name it is spaced but when Pete puts it up it is jumbled together. Her signature is different all around. (00:01:30 - 01:27:30)
Continuity mistake: When the Devil is a teacher in the classroom she is erasing homework assignments off the board. In the close up shots (and maybe 1 or 2 of the far away ones) the board's partially erased. In most of the far away shots however, the board isn't erased. (01:01:50)
Continuity mistake: Early in the movie after Haley Joel Osment befriends a bum they are sitting at the kitchen table and the bum pours Haley a bowl of Captain Crunch and fills it over the rim of the bowl. In the next wide shot the bowl of cereal is below the bowl's rim level as they pour milk into it.
Continuity mistake: When Greg is eating dinner with Pam's parents, his amount of sweet potatoes on his plate varies, sometimes there's many on his plate, other times there are less. (00:30:30)