Jerry Lee was played by Rando, a 3-year-old German Shepherd from West Germany. A year-long search was held to find the right dog for the role. Over 40 dogs were considered but none of the American German Shepherds were deemed suitable. Rando trained for 3 months with Karl Lewis Miller and learned to understand commands in English.
At the dinner party given by the gangster, there is a butler walking across a room behind a doorway. The butler was Michael J.R. Gill who was working with the catering staff hired for the film. After the filming, he actually served the food used in the scene to the cast and crew. Gill was not an actor, but was actually a real English butler and for seven years was butler to British actor Laurence Harvey, prior to his death.
When Dooley takes the dog to the hospital, he is seen placing his gun on the table at the head of the bed on which he lays the dog. In the very next scene just a second later, as the dog is being wheeled out to be operated on, the gun is back in his holster although he was never seen putting it there.
The car keeps changing from washed to unwashed throughout the movie AFTER the car wash scene. The washed car has a dent in the rear quarter panel, while the unwashed car has no dents.
When Jerry Lee is being aggressive with the two cops, whilst he is barking at them, you can see he's restrained with a lead around his neck. A moment later, he scamps away into the cop car.
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!