The role of Peter Venkman (Bill Murray) was originally written for John Belushi.
John Belushi was originally cast in the role ultimately played by Michael Keaton. However he died shortly before filming began, and the role went to Keaton.
Aykroyd said in an interview that the Chevy Chase role in Spies Like Us had been written for John Belushi.
Did you know that John Belushi was not the only choice for this movie? (click to learn more)