Revealing mistake: At the start of the movie where the nude woman jumps from her balcony, as she is falling and supposedly getting closer to the car, you can see after a couple of seconds, her body landing on the safety mattress thing, with a print on the top of it making it look like the street with parked cars. You can tell it is a mattress because just before they cut from the shot, the mattress dents inward. This could be taken for the top of the car denting in, except the dent "marks" extend from the sides of the roof of the car, into the bit of pavement beside the car. (00:04:05)
Revealing mistake: In one of the first scenes of the movie you see Riggs in his trailer. He walks out of bed smoking a cigarette and taking a beer. When he takes his first drink of the beer some fluid is spilled. If you look at it, it is not beer. It's probably water, but definitely not beer. (00:07:00)
Revealing mistake: When the General holds the lighter under Mr. Joshua's arm there is no smoke from burning hair at all. (00:23:50)
Revealing mistake: Riggs handcuffs himself to the depressed businessman. They jump off the building but they're not handcuffed to each other anymore. They used plastic cuffs which could separate during the stunt in case anything went wrong. They break just as they jump, so they grab each other's hands to stay in contact. After they land the cuffs are attached again. (00:31:00)
Revealing mistake: When Riggs walks up to the "Irish-Chinese" hooker it's raining quite hard, but not on him. (01:05:35)
Revealing mistake: When Murtaugh's car is going towards the meeting point, there's some extra dust coming from the right, caused by crew members. (01:12:55)
Revealing mistake: Early in the scene where the exchange for Murtaugh and his daughter is taking place in the desert, there are some aerial shots of a helicopter approaching the exchange site. The blades of the other helicopter, that is filming the aerial shot, can been seen at the top of the frame. (01:18:05)
Revealing mistake: The hole in the windshield through which the General's driver was shot is not a hole but a round spot of cracked glass. Only before the car gets hit by the bus there is a shot of a hole big enough for a bullet to zip through. (01:30:20)
Revealing mistake: Towards the end of the movie, watch the shots of the General in his car. Though he's supposedly speeding, the view we get through his rear windshield is of the ground going up and down, as if he was really just sitting in the car and pretending he was driving. (01:30:30)
Revealing mistake: When the car crashes into the bus and lands on its top, you can see a big square hole cut out of the car's underside. (01:30:35)
Revealing mistake: A short shot from inside the bus looking forward at the moment of impact shows a wall of water fires up onto the windshield. This 'water barrel' technique is used to lessen damage and injury on many public roadways, and is used here to save the bus for use in another take - the one when it actually does hit the car a split-second of movie-time later. (01:42:15)
Revealing mistake: When the bus hits the car, the car launches into the air, propelled by a special-effects 'roll cannon'. The cylindrical slug that is fired out of the bottom of the car is seen rolling ahead of the bus toward the bottom of the screen. (01:42:15)
Revealing mistake: In the wide shot of the bus colliding with General McAllister's car, look at the front seat of the bus and you can see that the driver is a mannequin.
Revealing mistake: During the fight sequence between Mr. Joshua and Riggs at the end of the film, Mr. Joshua lifts up Riggs and carries him on his back before dumping on the hood of the police car. You can see that Mr. Joshua is not Gary Busey but a stunt double.
Revealing mistake: As Joshua's chopper gets away, the camera follows it for a moment, then pans up to a long shot of the mansion. As it does so, the blades of the camera chopper can be seen at the top of the shot for a moment.
Answer: The jumper's name was Len McCleary. He was played by Michael Shaner and is credited for the role in the film (and on IMDB).
Bishop73