The jet fighter scenes are footage from Top Gun (1986). In one close-up of the fighter, the words "Lt. Pete Mitchell" and "Maverick" can be seen stenciled under the canopy.
Post-production ADR was apparently performed when some of the actors were not available. Thus, there are several points where they have been looped by other performers who only sound vaguely like them. In addition, Hannes Jaenicke's entire performance has been re-voiced by someone else.
In the final flashback sequence a clip from film Backdraft can be seen when a fireman is falling down an elevator shaft. This is when Steven (Kurt Russell) jumps to save Brian (William Baldwin) who had became trapped at the bottem of the shaft under a gas leak set a blaze