Murphy, after downing Montoya's helicopter says, "AH! Not again!" without moving his lips. In the same scene he says, "Ok chaps, How'd you like to follow my leader?" His lips say, "Follow my leader now!"
When Murphy and Lymangood are called into Braddock's office after the assault on McNeely, Braddock refers to the nude gymnast as "that silly twit out there in Encino," but his lips appear to voice something else. (The line in the script is "Don't you think I've heard about that silly c**t out there in Encino?")
Cochran claims it is impossible to loop a helicopter, yet such maneuvers have been performed since the 1960s, even by larger models such as the CH-53A, something a pilot as experienced as Cochran should know.
After Cochran's demonstration flight, where the main gun continue to fire after he released the fire button, he stated that he had a "stoppage". A stoppage would indicate the weapon stopped firing. He actually either had a run on, a mechanical failure of the firing mechanism. Or cook off, where the barrel got so hot it ignited the rounds as they were chambered.
One of the F-16's attacking Murphy fires an AIM-9L Sidewinder (short range air-to-air) missile at Blue Thunder from a distance barely two miles away. The AIM-9 travels at Mach 2.5, and from that distance the missile would have taken about four seconds to reach Murphy, yet Murphy has nearly fifteen seconds to avert the missile. From so close he would have had no chance to maneuver in front of the building in his attempt to fool the heat-seeking missile, let alone escape obliteration.
In the scene on the bridge over the L.A. river where Kate is stopped by "Metropolitan" Police, the younger officer's gun keeps switching from a Colt Python or Diamondback to a Smith & Wesson Model 15. He draws a Colt as he exits the car and brandishes a Smith & Wesson approaching the car and during the exterior shots of Kate's car. A Colt is seen from an interior shot of the driver side window which alternates with the Smith & Wesson exterior shots. A final exterior shot show a Colt as "Blue Thunder" hovers from the bottom of the bridge.
During the dogfight with Cochran, the starboard window of Blue Thunder's canopy is shattered and Murphy is injured. When Murphy takes Blue Thunder into the Immelman Turn, the damage is seen on the port side.
Early in the film Murphy and Lymangood respond to a crime in progress at the address given by dispatch as "8792 Linden Road". After the incident, Murphy tells Lymangood to call an ambulance for the victims below. Lymangood tells dispatch the address is "3920 Linden Road".
While Kate is rummaging through the drive-in theater dumpster, looking for the hidden video tape, Murphy flies up to keep an eye on her. However, the helicopter shadow seen on the back of the movie screen is that of a Bell JetRanger, not the modified Aerospatiale Gazelle.
The first time we see Kate, when she retrieves her blender from Murphy's house, her car is parked directly behind his. As she leaves, his Trans Am has disappeared and she drives straight down the road.
When Lymangood is being chased just before he is killed, his hands are taped together. After he is struck by the car and sprawls out on the pavement his hands are clearly free and apart. But when the EMTs are picking him up and putting him in the body bag, his hands are again taped together.
When Murphy goes home, he parks his car where there is a spectacular, overlooking view of the Los Angeles skyline in the background. This has to be an east to west view as there are no "heights" west of Los Angeles. In the view there is still light in the sky. The light must be from a sunset because, as we all know, the sun sets in the west. However, recall that Murphy works the night shift. In fact, when Kate arrives a few minutes later, the time of "three in the morning" in discussed. Obviously, the sun doesn't set in Los Angeles at 3 am.
Murphy is wearing street clothes when he gets into Blue Thunder to listen to Lymangood's tape. He is not wearing the green wristbands he wears when flying (and probably wouldn't have them with him), yet after he takes off, he is wearing them.
In the scene where Kate is stopped by the police on the bridge, a patrol car is clearly seen pulling in front of hers, cutting off her escape, but a moment later, when the police are distracted by the appearance of the helicopter, she drives away.
Cochran sabotages Murphy's Bell jet ranger by removing the cotter pin and loosening the nut on the throttle-control linkage bolt so it can slip out. Aviation bolts are always installed head-end up as a safety precaution to keep the bolt in place should the nut come off.
Long shotgun microphones meant to record sound coming from the surface while the helicopter is in flight would never be mounted on the top of the helicopter, directly below the rotor blades. Aside from the blades and engine drowning out any sound, the ground would not be within the pick-up pattern of the microphones, and there would be no way to maneuver them into correct position.
Just before Murphy and Lymangood take Blue Thunder out on their first orientation flight, all they get is a verbal briefing from the Army sergeant. Murphy's unfamiliarity with the ship is evidenced by his comment about its being "nose-heavier than the Ayatollah." In real life, a pilot would be forbidden to take a new ship out as pilot-in-command unless he had passed a full check ride and gotten a logbook sign-off from an instructor pilot already rated in that particular aircraft.
During the first night flight of Blue Thunder, JAFO asks if they want Big Brother active. When they both decide no, JAFO says "I got the fuse right here." He is actually seen to remove a light bulb from the annunciator panel, not a fuse.
As Murphy and Lymangood hover in Encino, the sky appears to be just after sunset. However Braddock later scolds Murphy for waking the residents at 10:30 PM while McNeely was being attacked in Brentwood. Later as Murphy arrives at home overlooking downtown L.A. with the sky illuminated, either just after sunset or pre-dawn. However moments later he scolds Kate for picking-up a blender at 3 in the morning. In summer months, the sun rises at 5:30 AM and sets at 8 PM at the latest.
When we first see shots of the F-16 aircraft, they are obviously models. They apparently only had one model and duplicated it for an early shot that showed two; since both aircraft had the tail number 068.
At the beginning of the final battle scenes Murphy is shot at by two F-16 fighters that miss, first blowing up a restaurant and then blowing out the side of a high-rise. In both instances the debris falling from the sky is obviously styrofoam and not concrete or steel.
The frame is reversed during a brief overhead shot when second police car approaches the drive-in theatre; traffic is shown keeping left, and the cruiser passes a light-colored vehicle on its right, but in the striped median.
The goof items below may give away important plot points.
When Murphy gets out of his car, to use the pay phone, after Lymangood is killed, he clearly closes the door of the car. When the LAPD squad car pulls up, moments later, the door on Murphy's car is standing wide open.
Shortly before Lymangood is killed, the white Chevy (which was shown with three of its four headlights illuminated) rams into the back of a parked car, smashing its front end and knocking out all but one headlight. However, when the Chevy is shown rounding the corner in front of the convenience store, the three lights are on again.
When Murphy sets Blue Thunder down on the railroad tracks in front of the freight train, the slow motion shots (from several angles) show the helicopter exploding from within before the train makes contact past the outer part of the helicopter's rotors.
In several shots of the dog fights between the Murphy and Cochrane above the streets of Los Angeles, the local police can be seen holding back and redirecting traffic away from the the shooting location.