When the Roci received the message from Gunnery Sergeant Draper's space suit the header for the encryption code was "TK4.21", an Easter Egg for a stormtrooper in Star Wars: Episode IV - A New Hope (1977). "TK 421, why aren't you at your post?". The code also ended with 1138, a popular Easter Egg to George Lucas's film THX 1138 (1971).
Episode title is "IFF". In military usage IFF means "Identification Friend or Foe", an automated system of radio frequency challenges and responses that allows weapon systems to know who to shoot.