Originally, the flashback scene of sick soldiers in the Korean War was a lot more graphic than what was shown. Some of the soldiers actually vomited onto the camera lens. However, it was decided that that took things too far, and it was taken out.
Frank Costanza tells Kramer about his experiences in the Army while serving in Korea. In real life, Jerry Stiller, who plays Frank, was an actual Army veteran. However, he served in World War II.
Bob Sacamano is a fictional friend of Kramer (Michael Richards). He is never seen but is the source of many bizarre anecdotes. Larry Charles has stated that Sacamano was a real-life friend, although the two fell out shortly after the character was first introduced. Throughout the course of the series he was referenced in the following episodes:
It's revealed that Elaine and Kramer are not Jewish. Contrary to popular opinion, neither are Michael Richards nor Julia Louis-Dreyfus (although the latter is of partly Jewish ancestry).
When asked, Jerry (Jerry Seinfeld) claims Gabe Kaplan, of Welcome Back, Kotter (1975), as his mentor.