A movie about 'nothing'
I can see some similarities between Diner and Seinfeld. Although Barry Levinson and Larry David each drew from their own lives, perhaps David was subconsciously inspired by Levinson like Elaine Benes was by the comic strip Ziggy.
The diner, obviously.
Silly conversations concerning word play. Diner with "nuance" and Seinfeld with George talking about "manure" on a date with a waitress from Monk's Diner.
The various girlfriends in and out of the guys' lives.
The over-attentive focus on trivial matters: Diner with the football trivia and Seinfeld with the red-dot cashmire sweater, the nose-picking, the perfect way to order from the Soup Nazi, etc.
Seinfeld is my favorite TV show of all time. Diner was very good, not quite great. Eddie was a dick for making Elyse take that quiz (I am a dude saying this), but hey, it was set in 1959 and it's only a movie, so I took it with a grain of salt. I guess I expected a little more from Diner, but it did its job.