When Jerry and Meryl argue about the can opener, a beer bottle on the counter keeps moving around.
Tanning beds have a timer and will shutoff when done. It is impossible to over do it unless the timer is set wrong or faulty.
Kramer (Michael Richards) wore goggles in the tanning bed so therefore should have a tan line around his eyes, but he doesn't.
During the fight between Meryl (Courteney Cox) and Jerry (Jerry Seinfeld) in the kitchen, a six pack of Henry Weinhard beer is on the counter. This beer is a West Coast beer and can't be purchased in New York.
Jerry and Meryl are arguing about a missing can opener and there is an automatic can opener on the wall right behind him that he could use.
Kramer (Michael Richards) says he takes baths when George (Jason Alexander) is talking about his shower activities, however in episode 7.15, The Shower Head (1996), Kramer had to take a bath due to low water pressure and was disgusted by bathing in his own bacteria.
When Jerry (Jerry Seinfeld) is on the phone talking to his parents, he accidentally presses redial. The sound is audible and Jerry looks down and presses the correct button to disconnect the call.