The production company was granted just one day at CalTech's new science building to film the extensive footage required. When the allotted time elapsed and an alternate location was unfeasible, the crew constructed a working elevator on a soundstage.
During the scene of his descent from the ceiling to straddle the bomb housing, Greg Morris had difficulty maintaining his balance. He slammed into the housing and suffered torn knee ligaments.
The IMF's target in "Doomsday" is villain Carl Vandaam. In North by Northwest (1959), cast member Martin Landau played Leonard, a henchman to James Mason's villain Philip Vandamm.
This is one of the few episodes where James Phelps is greeted on the tape with "Good morning, Jim" He would usually be greeted with "Good morning, Mr. Phelps.