While being picked on at the bar, Benny finishes his mudslide and noisily places the empty glass on the bar. As seen from the big guy's point of view, the mudslide in front of Benny is hall full.
The Rabbi's car is registered in New York State, but there are no Registration and Inspection stickers on the windshield.
Ben was upset that he was served a cheeseburger, which was not kosher because it mixed meat and dairy. If the restaurant was serving cheeseburgers, it's clear that the meat itself wouldn't have been kosher on its own. But Ben seemed not to have a problem eating a plain burger from it.