Burt Ward suffered 2nd and 3rd degree burns in this episode as the special effects crew took little precaution in ensuring the safety of others. The first evidence of this injury is revealed during the first scene in which cynical reporter Nellie Majors makes an appearance at a press conference in the Commissioner's office. At the beginning of this scene - as you'll notice in retrospect - Adam West is positioned so that he's standing in front of Burt Ward, obscuring the view of Ward's right arm. At one point, West steps forward to receive Mr. Freeze's delivery of "green ice"; as he does so, Ward's right arm is in plain view, and it can be clearly seen that a heavy gauze pressure bandage is wrapped around the length of his forearm, from wrist to elbow. Throughout the rest of this two-parter, both West and Ward are clearly maneuvering to hide this bandage, but it is accidentally revealed in several other scenes, including the ending shot of the Dynamic Duo in the City Hall elevator.
The two henchmen that impersonate Batman and Robin for Mr. Freeze are played by Hubie Kerns and Victor Paul, the stand-ins that are used during the fight sequences throughout the series. It is an in-joke when Mr. Freeze says that he would think that they were the real Batman and Robin from a distance.
Alan Napier appeared in Forever Amber (1947), which was directed by Otto Preminger. Napier found working with Preminger on the film to be unpleasant and had to hold his tongue when dealing with Preminger while working on the episode. The cast of the film also included George Sanders, who originated the role of Mr Freeze during the show's first season.
Reportedly, while Otto Preminger was deciding about taking the role as Mr Freeze, his grandchildren, who were big fans of the show, became so excited about the possibility, that they kept Preminger locked out of his home until he promised them he'd take the part.
The signs on the batpoles that read "Robin" and "Batman" are missing without explanation.