Revealing mistake: In the scene where Amy lets Wayne know that breakfast is ready, she presses a button labeled breakfast. There are other items on the box, such as lunch, dinner, and phone. When they show the board flashing the word breakfast, you can see that the word breakfast is the only word the board can display between flashes.
Factual error: After their parents give up looking for the kids, there's a "time passing" scene showing the lit attic window from the outside of the house, in which the night grows lighter until it's morning of the next day. But the moon in the picture doesn't move. How can the moon stand still if time is passing?
Continuity mistake: When the four kids run and hide from the ant after he takes over their cookie, Amy has no cream filling on her mouth, but when she tells Ron to be quiet, there is cream on her bottom lip.