It was intended that Herbert Marshall reprise his role as the police inspector, but due to illness he was replaced by John Sutton.

Phillipe hires Alan Hinds from Delambre Frere and uses his own finances, but the funds run out before the equipment is complete.

Holmes kills the rodent and puts the dead agent in his car, which he sends into the Saint Lawrence River.

He waits for Holmes to arrive and kills him, too, then returns home, where Inspector Beecham has found and captured the Phillipe-headed fly.

Kurt Neumann, who directed The Fly, died in 1958 so Robert L. Lippert, who financed the original, had to find a new director.

[7] During a particular dialogue scene, actor David Frankham rather conspicuously handles a cane, which closely resembles the wolf-head walking stick famously utilized in Universal's film, The Wolf Man (1941).

Return of the Fly features a commentary by co-star David Frankham and another by horror film historian Tom Weaver.

The original Teenage Mutant Ninja Turtles animated series references the film in a third-season episode by the same name.