Continuity mistake: After Dennis punches Spence in the nose the piano starts playing and Dennis just pushes it to turn it off even though every time they had to turn it on and off before then they had to use the on/off switch. (01:01:40)
Continuity mistake: When Spence's brother in-law almost crashes into Dennis' girlfriend's car, he's driving straight down the road and she makes a left from the intersection to cut in front of him, but when the camera angle changes back to the inside of the brother in-law's car the intersection that he should have just passed is nowhere to be seen.
Continuity mistake: When Dennis and Spence are trying to outrun the cops in the car that Spence stole from the racetrack, the camera shot from the inside shows them driving on a regular street with the yellow lines and everything but the camera shots from the outside show them driving on blacktop streets with no lines whatsoever.
Continuity mistake: When the doped up Turnip runs past Binky, multiple takes have been sloppily edited together; Binky is giving Turnip a thumbs up in the first shot, then after a cutaway he is shown with his hands on the steering wheel, but taking one off to give the thumbs up, and finally he is again with both hands on the wheel. (01:22:10)
Plot hole: The whole premise of the movie makes zero sense. Spence finds out that a certain race is rigged, but he is caught eavesdropping, so the goons are after him. They don't catch him and then the day after they stalk the betting counter looking for him. He then enlists the help of his friend Dennis to distract the goons so he can place the bet. But the villains are completely unaware about Dennis' existence! He could simply walk in and do the bet himself. He even is the guy with the money. No reason at all is given why Dennis does not place the bet himself, cash in, and walk away. Other than the fact that the movie would be done in 20 minutes and with not much of a payoff.
Revealing mistake: A farcical comedy movie does not need to have the most realistic action, but when the protagonists' Volkswagen Thing gets shot down by Turnip's double barrel, the engine 'explodes' with real flames and all, but no bullet holes at all in the metal. It's like it died from being scared. Fun part is, later the detective shows up at Spence's house and mentions exactly bullet holes. (00:28:25)
Continuity mistake: Round two of the police firing at the door of the mobster begins. After Denny's girlfriend shows up at the door, we see the police in an external view. To the left of the frame, you can see 2 officers with shotguns positioning next to the car, and two more, one with a rope on his shoulder, are arriving by the captain. In the next shot, the rope guy and his buddy are still arriving, but they are followed by cops with shotguns, which are going where there were already supposed to be in the previous shot, and missing now. (01:18:50)
Revealing mistake: Binky and Turnip are waiting for Ted Danson to show up at the racetrack to place his bet. Turnip starts the first sequence peeping from holes carved into the magazine. As he begins walking, notice an old man with a grey jacket and a blue shirt, reading a newspaper, sitting, and immediately after he comes in frame, an elderly couple coming in from the left. The man is wearing a brown suit and shirt about the same colour. When there's the first cut (after the odd guy sticks the tongue out), the two are rushing towards the entrance, opposite way from before, and there's the blue shirted old man standing, and a moment later there's the brown shirt guy passing by, just fresh off walking in and with another person, not the woman from before. The same guy is also seen in the bathroom in the next scene. (00:18:20 - 00:20:10)
Revealing mistake: When the two gangsters get to the racing tracks entrance searching for Ted Danson, look at the old lady in the background. You'll know which one instantly, because she is looking at the two gents. The two guys are kinda conspicuous, so you might think it's pretty fair and there's no fourth-wall breach here. Same thing when she obviously cracks a laugh when the two make their hasty exit after Stuart Margolin gets hit in the gut by a silent moustached man, it makes sense. But, right after the two exit stage, she casts a look right into the camera, and for the rest of the shot (as Danson and Howie Mandel enter) she peeks again a couple times. (00:20:20)
Continuity mistake: Dennis has just argued with the manager about the fuzzy slippers at work. He is skating off to deal with the last delivery. When there's a cut, notice how there's a man with a white jumper leaning against the white Cadillac, facing the guy with the red jacket. That man in white was not there before. (00:10:15)
Continuity mistake: Dennis followed by Spence is walking out of the bathroom with a handful (soon mouthful) of soap. Camera outside, and to walk out of the bathroom behind them, a guy with a blue jacket who was nowhere near the door, and not one of the two people who were instead seen headed towards the door. (00:21:45)
Visible crew/equipment: Binky and Turnip chase the protagonists after they cashed in. They crash into a toy stall, with the crash shown in a quasi-POV shot. To get that shot, a camera was mounted inside the car, obviously. The problem is, for the next 3 cuts, you can see that camera. (00:27:50)
Visible crew/equipment: The two protagonists cash in the win and are running from the goons who chase them. The car of the two baddies is parked outside. During the sequence when the car loses the second door, you can see reflected with great detail the camera crew and stage lights, right in the side of the car. (00:26:50)
Continuity mistake: An enraged mafia boss throws the billiard ball to Turnip, who ducks it. The ball after the impact with the door bounces off with a downward trajectory at sharp angle, and yet the next slapstick gag sees Binky, standing a few meters away, hit in the forehead by it. (00:34:20)