Continuity mistake: When Zack and Enrico are driving along, and they swerve past the car, two cars behind them on the road disappear, and the markings on the road completely change between these shots. (00:56:30)
Continuity mistake: When Zack opens the cooler to see the heart, the level of ice cubes in the cooler lowers between shots. (00:58:00)
Continuity mistake: When the engine falls from the back of a truck, Zach is driving his van perfectly in the right lane, but when in cuts to a closeup of the wheel of his van driving over the engine, he is now driving so half of the van is in each lane. (00:58:25)
Continuity mistake: When Rowan Atkinson and Wayne Knight are in the van, there is a car in the lane beside them. When they switch lanes, this car which should be behind them is gone. (00:58:50)
Continuity mistake: In one shot as Duane and Blaine drive over a big hill, while chasing the key-cutter, if you look at the hot-air balloon, the white rope that hangs from the basket has gone for this shot. Also, throughout the chase scene, the length of the rope differs. (01:00:35)
Continuity mistake: When Duane and Blaine are chasing the key-cutter who stole their key, they drive over the same hill and land twice - note the same tree stump they pass twice. (01:00:40)
Continuity mistake: Throughout the chase-after-the-hot-air-balloon scene, the hood of the blue car that Blaine and Duane drive differs from dusty to sparkling clean from shots. (01:00:55)
Continuity mistake: As Duane is about to hit the first cow in the field, the direction it is facing changes instantly between shots. (01:01:25)
Continuity mistake: After dropping from the hot air balloon rope, Duane looks up and sees the car with Blaine on the hood, driving towards him. He gets up and starts to run away from the car, and behind the car in this shot is just field - previously there were cows in the field. The position of the cows change in a few following shots too. (01:01:45)
Continuity mistake: In the Balloon Chase scene, if you watch the sky it changes a couple of times. One time it's overcast, the next it is evening and the sky is orange. (01:02:25)
Continuity mistake: Duane sprays the key-cutter's face with milk from the cow's udder, and his face is wet, and covered in white milk, but in the next shot the white milk has gone. (01:02:35)
Continuity mistake: When Blaine drives through a wooden fence into the monster truck race, we see the grille of the car intact, but it was seriously damamged, when it hit the rock by the oasis in an earlier scene. (01:02:55 - 01:22:55)
Continuity mistake: At the Monster Truck Rally, the blue convertible that they are driving has no dents or scratches, it looks perfect. But in the scene before that they are doing nosedives into the dirt while chasing the hot air balloon. You can clearly see the damage then. (01:03:10 - 01:27:30)
Continuity mistake: When the bikers destroy Hitler's car, they break off the front left flag. Later, when Hitler's car crashes into the WWII veteran convention, the flag is back. You can also see it is back later when the people come to collect it from the diner car park. (01:07:40)
Continuity mistake: As the bikers smash Hitler's car, one of them smashes a headlight, and there's still glass and fragments in it, but in the next shot the whole headlight is intact again! (01:07:45)
Continuity mistake: Between shots the bikers riding beside Hitler's car change. (01:07:45)
Continuity mistake: When Vera and Merrill enter the tent and start drinking and sucking ice cubes, Merrill's red and black scarf is spread out across her arm/shoulder and is falling out, but it is neatly hanging around in the next shot. (01:13:35)
Continuity mistake: When Vera and Merrill sneak up to the rocket car, and start pretending to present it, there are two men speaking by a stand, which has six microphones standing on it. However when Vera and Merrill start the rocket car up, we see the two men turning round to look, and now two of the microphones are lying down on the wooden stand, and a seventh mike has appeared. (01:14:15)
Continuity mistake: When the car repair man cries "Oh Lord, I'm here. And I'm listenin'" the oil rag he holds in his hand changes from being dark red to a much lighter red between shots. (01:15:50)
Continuity mistake: In the single outside shot of the "Fatburger" diner, when we hear Bev saying "right, everybody OK? You alright..." look at Hitler's car, parked out front - you can see that the front windsheild (which got smashed earlier) is either missing or intact, because no smash marks are visible. (01:16:10)
Answer: They only had blanks - the non-cut keys that are used to make keys. So when they saw those, they knew that the guy had their key.
wolfchild