Continuity mistake: When the children hear the bump coming from upstairs, they go to investigate. Conrad says "it sounded like it was coming from the closet." The closet is facing the stairs when they go up them. Later in the film, a shot is shown where you can see the rooms in the whole house together. The closet isn't on this shot, so where has it gone?
Continuity mistake: In the scene where the cat's tail accidentally flips Sally onto the couch,we see that the couch is very far away from where the cat is, yet after a 2 to 3 second shot of a CD player coming out of the cat's hat, we see Sally standing behind a chair right in front of the cat, this is impossible as no human can move this fast.
Continuity mistake: When the Cat is juggling all the items in the beginning, he has a cake on his hat. After he burps and everything flies up he catches everything but the cake is now gone and never appears again.
Continuity mistake: The first time Lawrence comes in (as the trio are jumping on the couch), he starts sneezing while standing under the Cat. He's in the middle of the living room and facing the front entry; but in the next shot, he's on the edge of the living room and facing in. He jumps back and forth throughout the scene.
Continuity mistake: In the scene at the birthday party, when the trio is at the window looking inside a shot shows them turning and yelling. It goes to another zoomed out shot, but they turn a second time.
Continuity mistake: In the scene where Alec Baldwin is in the house to discuss Conrad going to military school he is dressed for work. He puts his briefcase down and sets his sunglasses on top of it. In the next scene the glasses are behind and to the side of the case and in the next scene they are back on top of the case. And so on.
Continuity mistake: When Larry first arrives at the house there is a screen door attached to the front door, which he holds open. In all other scenes the screen door is gone.