The original script had the episode taking place in 1985, but was changed to 1981. However, the ending scene has Lt. Ellis and Mark Bradley drinking a bottle of champagne with a 1984 vintage.
On the "Collector's Edition", "Digitally Remastered" DVD boxed set, the actor's voice track drops out at several points. The background audio continues.
There is no sound effect when Captain Carlin pulls back the control stick to launch sky-diver.
The UFO is severely damaged after being hit by a missile from Sky 1, but how did it survive completely intact after colliding with the interceptor.