Continuity mistake: The lawn goes from established grass to freshly laid sod back to established grass. In the daylight scenes you can tell that the grass is growing, probably 4 inches tall, not mowed recently. During one of the night scenes about half way through the movie, you can see that the grass is kind of sickly looking and you can also see the lines around the strips of sod. The next day while the kid is doing his soccer stuff, the grass is back to green and uncut.
Other mistake: When Mr Tinkles & Co are in the car outside the flocking factory, you see them speeding around the corners wildly, but if you look on the floor there are already treadmarks from previous takes.
Continuity mistake: In the Mason Flocking factory, just after Butch says "I've got to find Lou," the camera shows the window of the office, and the blinds covering the window can be seen hanging at a steep angle. In the shot before Lou pulls on the rope, you can see Scotty's head, and behind it, the blinds are straight.
Continuity mistake: When Buddy is chasing the cat through the house at the beginning of the movie, there is a shot where the cat is sitting down at the end of a corridor. The shot changes and gets in closer to the cat, which is now standing up.
Continuity mistake: In the same scene as above, the kid's dad comes out of his lab with a bunch of wires all over him, and a mask on. When a camera shows an outside view and you can see the parents' shadows on the curtain, you can see his dad has no wires on him, and no mask.