Continuity mistake: In the scene on the bridge when Frank's girlfriend gets pulled over, the cop on the driver side has his gun drawn. It changes between angles. From the outside it's a standard issue 38. From the inside looking out it's a .357 magnum.
Continuity mistake: When Lymangood is running away from the car he crashes in to a bike and his hands and arms are free, not tied at all.
Continuity mistake: Before Frank destroys the Thunder it's daytime - a few moments later it's completely dark.
Continuity mistake: When the Thunder is shown for very first time the sun is barely rising, but at the time it gets to the training field the sun is high like it's noon.
Visible crew/equipment: The helicopters are flying low above the streets chasing each other. Several forward looking shots show no to very little traffic, and one blatantly shows two cops directing traffic away from the set of the film.
Character mistake: Following Lymangood's death, police dispatch radios a BOLO on Murphy, identifying his vehicle as a 1979 Trans Am. However Murphy drives a Turbo Trans Am, only available in 1980 and 1981. Dispatch should have all of his data available.
Chosen answer: Murphy has been deemed a threat to the public at large by the authorities, having "snapped" and stolen an armed helicopter. Cochrane is using that determination as cover to finally kill Murphy, whom he's long despised. Killing Murphy on the ground would be harder to get away with. He would not be responsible for paying for the helicopter anymore than the Air Force or the other police helicopter crews would be had they sucessfully knocked Blue Thunder down.
johnrosa