Filming began at Elstree Studios. As it was under threat of closure, the entire production moved to Pinewood Studios one weekend. All the sets had to be rebuilt. As a result they were blacklisted by the unions.
Nick Tate was originally cast as Collins. Another actor was originally cast as Nordstrom but became sick after the special milky contact lens had been made- it had to be used for the replacement actor Roy Scammell.