enlisted to protect Benes Raquel Welch as Cora Peterson, the technical assistant for Dr. Duval Edmond O'Brien as General Alan Carter, one of the officers in charge of Combined Miniature Deterrent Forces Donald Pleasence as Dr. Michaels, CMDF's medical chief and a circulatory specialist later revealed to be the saboteur of the mission Arthur O'Connell as Colonel Donald Reid, the operational commander for Combined Miniature Deterrent Forces William Redfield as Captain Bill Owens, a U.S. Navy officer who designed the Proteus for his branch's research and development program Arthur Kennedy as Dr. Peter Duval, a top-class brain surgeon enlisted to perform the surgery on Benes Jean Del Val as Dr. Jan Benes, the comatose scientist who perfected the formula for unlimited miniaturization Barry Coe as communications aide Ken Scott as a Secret Service agent Shelby Grant as nurse James Brolin as technician Production The film was the original idea of Otto Klement and Jerome Bixby. They sold it to Fox, which announced the film would be "the most expensive science-fiction film ever made." Richard Fleischer was assigned to direct and Saul David to produce; both men had worked at the studio before. Fleischer had originally studied medicine and human anatomy in college before choosing to be a movie director. Harry Kleiner was brought in to work on the script. The budget was set at $5 million. The budget went up to $6 million, $3 million of which went on the sets and $1 million on test footage. The Proteus submarine was constructed as a full-size set piece 42 feet long, first seen in the "miniaturizer" room and later in scenes set outside the lung and inside the inner ear, when the cast was to be seen "swimming" (actually suspended by wires) outside the submarine. The full-size Proteus mockup contained all the interior sets that the actors are seen in to represent the interior of the submarine, with sections that could be pulled out to allow for cameras and crew to film the interior. The submarine was also constructed in miniature, including a large miniature around five feet in length that could be flown on wires in the abstract sets representing the inside of the human body. The heart and brain sets built to accommodate the five-foot miniature filled a soundstage on the Fox lot—these were filmed "dry for wet," with floating, blob-shaped elements meant to be blood cells filmed separately