Director Keith Gordon took a small role in I Love Trouble (1994) so he could get this script to Nick Nolte, whose agents thought the project was "too small."
The character Howard W. Campbell Jr. is used by Kurt Vonnegut Jr. in the novel Slaughterhouse Five, and makes an appearance in the movie of the same name, although in reference to a part of Campbell's life not included in the film version of Mother Night.
"Frank Wirtanen" is the name of the man who used to sell Christmas trees to the Vonnegut family.
While they are hiding out, Campbell (Nick Nolte) says to Resi and George, "In spite of everything, I still believe people are really good at heart," a direct quote from "The Diary of a Young Girl" by Anne Frank.
John Goodman's character's name Wirtanen is the most common surname in Finland (usually written with single V).
Lieutenant Bernard O'Hare, when he captures Campbell, is not wearing the regulation M1 helmet of WW2 vintage, nor are the two U.S. soldiers who drive Campbell away from the concentration camp. Rather, they appear to be wearing the British paratrooper type-3 helmet, which, interestingly, was adopted by the Israeli Defense Forces in the late 1940's and '50's.
Cameo: [Kurt Vonnegut Jr.] Towards the end of the film when Campbell (Nick Nolte) stands frozen in the street one of the people who pass by him in slow motion is the author of the book the film is based on (the man with a mustache in a beige suit and a blue shirt with a tie.)