The Colossus costume was eight feet tall, weighed 160 pounds and was made from burlap, plastic, rubber and fine chicken wire. Inside, there were batteries, cables, air tanks and oxygen tubes.
It took stuntman Ed Wolff (who was 7 foot tall) 40 minutes to climb in and out of his Colossus costume so a special rack was built where he could rest whilst still in costume in between shots.
The film features an unusually restrained piano score by Van Cleave. This was not so much an artistic choice but brought about by a musicians' strike.
The funeral sequence had to be reshot because actor Ross Martin, who was in the coffin, fell asleep and his snoring drowned out the recorded dialogue.