K-9 (1989)

Continuity mistake: In the scene where Belushi and Jerry Lee (the dog) enter the warehouse, Belushi askes everyone to stop what they are doing and even has the forklift driver lift him up so he can talk to them. Once he is done talking, he tells the lift driver to bring him down. The next few shots where they show Belushi walking to his car, if you look closely, you will see that the fork lift is back up in the air, but there were no sounds and there isn't another lift to be found. (00:25:05)

Continuity mistake: During the car chase between the Mustang and the Mercedes, the cream on Jerry Lee's face changes throughout. (00:56:25)

GalahadFairlight

Other mistake: In the bar scene where Dooly is being beat up by the bar thugs, When Jerry Lee starts to attack them there is a shot of the dog lunging at the thugs. If you look carefully at the shot the dog is fake. You must look very carefully it is only a second. (00:32:30)

Dooley: Alright, let's get one thing straight: The woman is mine! Now we're both members of the animal kingdom. You know that and I know that. And we both know that this thing is really primal. So if you think you're such a badass you just try that one more time and you're gonna end up in a pet cemetary! You remember the movie Old Yeller? You remember when they shot him in the end? I didn't cry! Now come on.

Lyman: Dooley, what is it about me that makes you so passionate?
Dooley: Well, it's not your looks, Lyman. I guess it's your job.
Lyman: And knowing your methods of law enforcement, I don't suppose that you have a search warrant?
Dooley: Dog ate it. You can hang around his tail for an hour.