Tom Poston was scheduled to play Smart when the pilot was first offered to ABC. When ABC turned it down, NBC picked it up on condition that Don Adams play the role of Smart. Barbara Feldon was the producers' first and only choice to play 99.
86 drives a Ferrari not a Sunbeam Tiger in this episode.
The opening scene depicts Max' shoe phone going off during a concert, much to the confusion and consternation of the other guests sitting near him. In his voice-over commentary on the DVD of this episode, co-writer and series co-creator Mel Brooks can barely contain his glee at his own prescience in imagining such an incident at least 20 or 25 years before cell phones existed, which now cause similar interruptions in public gatherings all the time.
Pilot episode "Mr. Big" was the only black-and-white episode.
While this episode survives in black and white only, presumably at least part of it was filmed in color as the opening credit sequence of Smart walking down the hallway of ever more secure doors is identical in every following episode until the end of the series, implying it was never re-shot.