Continuity mistake: As Buddy walks out into the street at the start of the movie when the cat is playing dead, you can see several parked cars on the street behind him. When the van backs up to 'catnap' buddy, there are no parked cars. Then as the van drives off again, there is a different bunch of parked cars in the street. (00:03:54)
Continuity mistake: It is clear throughout the movie that the dog that plays the character "Lou" changes from a male to a female. You can tell in different scenes when Lou is standing up, it's a male dog, and when Lou is laying on his back, belly facing up, it is a female dog.
Continuity mistake: When the cats drive into the factory the same hubcap falls more than once from the car. (00:50:55)
Continuity mistake: When Mr. Tinkles starts the room on fire at the end, parts of the room that are nowhere near the fire, are on fire.
Continuity mistake: At the beginning of the movie, a woman takes a pie out of the oven, leaving the oven open, and then gets hit by the cat flying through the window. As she falls back, the oven has magically shut. (00:02:40)
Continuity mistake: At the very beginning of the movie, as the 4x4 draws up outside the house, a woman (Carolyn) jogs past. However, in the next shot, the same woman has now moved back along the road, and jogs past the 4x4 again. (00:01:10)
Continuity mistake: When the kid is home after the soccer tryouts and he does not get in he kicks his soccer ball and misses the goal. Seconds later he kicks another ball, despite not having one there. (00:33:15)
Continuity mistake: When the cats are having a meeting and the maid comes in, she picks up Mr Tinkles. She goes to put him on her left shoulder. The camera quickly cuts and he is on her right shoulder. When the camera changes angles again the cat is on her left shoulder. (00:19:35)
Continuity mistake: When the boy is playing with Lou he rolls around in the mud, seconds later there is no mud on his knees or his bottom.
Continuity mistake: When the video of Mr. Tinkles threatening to 'put the Brody family to sleep' is seen in the background at HQ, it is noticeably different to when the dogs saw it first time. This is easier to verify when Mr. Tinkles says, 'they will be put to sleep.'
Continuity mistake: When Lou walks knocks the door into the burning room where the kid and his parents are, you can see that Lou has a circled chain. However, in the next few shots it appears as a bone shaped chain and then it changes back to the circled chain. (01:14:40)
Continuity mistake: When Buddy the Bloodhound is chasing the ginger cat through the womens' house at the beginning, you see a shot of the cat from Buddy's point of view which shows the cat sitting down. Yet in the next shot that zooms in on the cat, it is standing up. (00:03:10)
Continuity mistake: In the scene in the flocking factory when Jeff Goldblum's character is being confronted by the cat leader (Mr. Tinkles) another cat (Calico) is on Goldblum's shoulder. When the shot changes to an angle behind Goldblum, Calico disappears only to immediately reappear when the shot changes back to the angle facing Goldblum.
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.
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.