The sound of Number 5's laser firing is the same effect as the Ghostbusters' Proton Packs powering up.
Filmed in the town of Astoria, Oregon, where Free Willy, The Goonies (1985) and Kindergarten Cop (1990) were filmed as well.
Three interchangeable radio-controlled heads were built for Number Five so facial expressions could be properly articulated according to the scene.
As per the movie's attempt to portray a living robot in the "real world," every part of Johnny and his brethren was built to have a specific, logical purpose behind them. This was originally a source of contention between director John Badham and the robots designer Syd Mead, the latter of whom insisted on giving Johnny "eyes" to give the character a method of visually expressing emotion. As a result, Johnny's iconic "eyelids" were created, with the explanation that they were sun guards and camera coverings.
The house, used as Stephanie's house, still exists, and is located at 197 Hume Avenue, Astoria, Oregon. In November of 2019 it sold for $340,000.