Continuity mistake: In this episode, George asks Russell if his last name contains a "y" and Russel answers that it doesn't. However, Russel is credited in this and subsequent episodes as "Russell Dalrymple."
Factual error: Kramer gives Jerry a two-line phone for his birthday, which Jerry plugs in and immediately uses. But a two-line phone requires the installation of an actual additional phone line. What Jerry was using when the NYU reporter overheard him "admitting" he was gay was simply call-waiting.
Factual error: In the episode where Jerry is upgraded to first class while Elaine struggles in coach, the scene changes to show a plane flying with the colors of Southwest Airlines, and you can make out the name "Southwest" written on the tail if you pause as it's landing. Anyone who has flown them knows that there is no first class on Southwest.
Continuity mistake: While discussing Candice Bergen with Jerry, George picks up a menu and places it on the table; both he and Jerry have a menu. In the next shot showing the table (when George says, "I can't believe I missed Kramer,") both menus are flipped: in the first shot, white pages are facing up, and a yellow page is on the back of George's menu as he picks it up; in the second, the yellow sides are facing up. (00:01:02)
Revealing mistake: After The Old Man's dentures are destroyed in the garbage disposal, he shouts that his dentist is "downtown." There is sibilance audible in his production of the T sound (after the stop release). Sibilance is high frequency noise cause by turbulent airflow directed at the front teeth vibrating randomly in a small space; if he had no front teeth, there should be no sibilance. (00:14:35)