Not sure about holes but I always find inconsistancies. For example in an earlier episode of Seinfeld George mentions he's in a rush because he's double parked and a few seasons later in "the dinner party" he notes that people who double park should get the chair
I don't think that is an inconsistancy - George is a self indulgent prick and I wouldn't be suprised if the writers were aware of those two scenes.
Also I am pretty sure George suggested Kramer double park when they were looking for a spot, so yeah it is just George being self-centred.
If you want inconsistencies in Seinfeld, in one episode Kramer says he takes baths yet in a later episode (I think the low flow shower head episode) he explains how disgusting a bath is.
Also I think one episode he mentions how he wears boxer shorts yet in a later episode he can't stand wearing them.
True story, happened to a friend of a friend of mine.