Continuity mistake: When Governor Tracy is filming an ad, a wide shot shows there's nothing on the lawn in front of her. When she finishes her speech and the shot changes, the crew and equipment suddenly appear. (00:14:40)
Audio problem: The last scene begins with Al and Mike walking towards the plane speaking. Al asks "are you sure you don't want a job on my staff?" Mike then responds by stating; "you know what Al... I don't really think I'm cut out for politics." Al then is heard laughing at this. It is very clear the audio laugh is actually that of actor David Spade and appears to be placed over a most likely silent smile of Al. (01:20:00)
Revealing mistake: When they're trying to get rid of the bat at the cabin, they hold up a sheet to force it out of the door, however when they reach the door, you can see the bat being pulled up with string or wire.
Revealing mistake: Watch the scene where they're headbanging and the tape keeps going out. You can see where they splice the scene in because the trees change in the background instantly.
Continuity mistake: Chris Farley and David Spade are driving in a borrowed police car. When the camera is on Spade, the window is not open, then it is open a bit, then it is closed again.
Continuity mistake: After Spade gets foamed, in the scenes to follow, the foam stains change many times, in addition, he has his coat on, then off, then on again in different seems, and the coat never seems to have any foam either.
Revealing mistake: After the roof blows off the cabin, the hail starts falling inside the cabin. It is fairly obvious that the hail is just being poured onto the cabin. Its most noticeable just after the hail starts falling on the cabin, there is a shot taken from inside the cabin you can tell by the night sky and some of the trees outside that there is no hail in the distance.
Continuity mistake: When Steve gets foamed by the farm boys, he has tan trousers on. When he goes back to Mike, his pants are dark. When he meets Mike, his trousers are tan again.
Continuity mistake: Near the end when Mike is on top of Governor Tracey, the camera pans to a wide shot and there's no sign behind the people on the stage. In the newspaper picture of Mike on top of her, there's now a sign behind the people.
Continuity mistake: When the boulder is coming down, the front door is open. When we get a shot of the front of the cabin, the door is now closed. However, the doorknob switches from being on the left to being on the right. We also see there is nothing hanging from the porch roof. Before Mike and Steve crash through, we see the front again and the doorknob is back to the left and there's a metal star hanging from the porch roof.
Continuity mistake: When the boulder hits the cabin and Mike falls out the front door, he's rolling, almost off the door, and on his side, with his back close to the rocks. There also is nothing on the back of the door. When it cuts to the close up, Mike is now face down on the door completely, with a dartboard on the door.
Revealing mistake: When Mike crashes the truck into the movie marquee, some of the light bulbs explode well before the truck hits them.
Continuity mistake: When Mike is playing football on the field, he scores a touchdown, and throws the football down. Then it cuts away to the kids complaining, then back to Mike, and the lost football is in his hand. It cuts to a larger view of the scene, and where's the football? The camera cuts away again, and then back to Mike and his team. The football is once again in Mike's hand.
Continuity mistake: Near the end of the movie, while at the Governor's mansion, Drake Savage (played by Gary Busey) is in a tree with a rocket launcher. He jumps out of the tree and lands without the rocket launcher. In the next scene, he jumps onto the stage and he has the rocket launcher, which he left in the tree.
Revealing mistake: When Mike is on his way to go vote and he falls down the hill, he gets to a spot where it isn't steep enough for him to be moving fast. If you look closely, you can tell that the editors of the movie fast-forwarded it to make it look like he is rolling down the hill really fast.
Continuity mistake: When Chris Farley is at the top of the hill, he then slips and falls for a little while. He finally gets to a place to stand up, and his blue shirt is covered in dirt. He then falls again, and when he reaches the bottom, he stands up, and his blue shirt is completely clean.
Audio problem: When Mike is being attacked by a bat in the cabin, after David puts the cover over his head, you hear a glass break. That was supposedly the shelf behind him, yet there was no glass on it.
Revealing mistake: When Mike slips and falls down the hill you can clearly see that he is pushing himself down as he goes.
Continuity mistake: When Chris Farley helps the old couple in the grocery store parking lot, he slams the trunk closed and his tie falls out of the trunk. Then the scene cuts to the old couple driving off and dragging him behind.
Continuity mistake: When Chris Farley falls from the TV van anntena thing he is going to land on his left shoulder but in the scene where he hits the ground he goes down on his right shoulder.
Answer: A major police department would probably not allow modifications to an official vehicle, even if it was assigned permanently to a particular officer, due to safety or insurance concerns. That said, many departments do use high performance or exotic vehicles seized during crimes under various forfeiture laws. Most times these are for promotional purposes, but I do know of a Florida department that used a souped-up Dodge Hemi-Charger painted in standard department livery for traffic enforcement.