Gwynne Gilford was pregnant during filming and the production team had to hide her stomach in most of the shots. That baby is now actor Chris Pine.
Dennis Christopher adamantly wanted to do the rooftop stunts, but the producers insisted on using a stuntman.
Chris Stein of the new wave group Blondie was the original choice to compose the soundtrack but his deal was canceled.
Horror of Dracula (1958) clips were used during the Dracula scene after Universal Studios denied permission for the filmmakers to use clips from Dracula (1931).
When writer/director Vernon Zimmerman approached Irwin Yablans with his pitch for the movie, Yablans presented him with a similar screenplay he had written two years prior entitled "Alex". Zimmerman then incorporated some of Yablans' ideas for "Alex" into his own script.