After filming was completed, Lou Costello was bedridden for several months due to a relapse of rheumatic fever, which he originally battled in 1943. As a result, the duo did not make another film together until Abbott and Costello in the Foreign Legion (1950), a year later.
The original script 'Easy Does It', was originally intended as a vehicle for Bob Hope. After the huge success of Bud Abbott Lou Costello Meet Frankenstein (1948), Universal-International wanted another "horror" comedy with Bud Abbott and Lou Costello, so the script was rewritten for them. Oddly enough, the role played by Boris Karloff was originally written for a woman.
When Angela comes to visit Freddie in his suite, and they sit down on the sofa, her right arm is down near her lap. Then, when the shot shifts to the side, her arm is resting behind Freddie on the back of the sofa.
During the opening credit animation, after machine gun fire writes "Meet The Killer", the animated Costello says, "You didn't dot the 'I'!". This wouldn't be necessary, however, since the words are written in all capital letters.
When Abernathy is looking over Freddie's shoulder during the so-called Bridge game, he starts on Freddie's right side. Then, after the camera cuts back from the close-up of Freddie's hand, Abernathy is on Freddie's left side.