... So The Alien Wore Trousers

In a magazine article the special effects department at Universal admitted that the "mutant" costume from the 1955 film 'This Island Earth' originally had legs that matched the upper body but they had so much trouble making the legs look and work properly they were forced by studio deadline to simply have the mutant wear a pair of trousers. Posters made to promote the movie show the mutant as it was originally supposed to appear.