Deliberate mistake: When Lilo is told to think of a name for her "dog" while at the Aloha Animal Rescue, there's an adoption document on the desk. The document's paragraph is in fact an acknowledgment of appreciation for this movie's production. Although it's only briefly seen twice, there's sufficient time to read a few words, such as "project Lilo and Stitch" or "at Disney-MGM Studios," and particularly in the close-up as it's being stamped "making of Lilo and Stitch," the last words of the paragraph. (00:27:00 - 00:27:25)
Deliberate mistake: When the roller skate with Scrump explodes, just as Jumba is blown backwards, notice the hallway's left wall with the doorway into the kitchen (this doorway is beside the stairs) is deliberately gone in this shot. That hallway wall with the doorway reappears properly in the next shot and a following shot. (01:00:30)
Answer: There are two times when this happens the first time he is holding his guns. The second time he is holding a frog.