The brief first exterior shot of Mario's Pizza actually shows a store front with a different name, "Five Roses Pizza". Near the end of the episode a different exterior is shown, and this time the store front is completely different and does display the correct name, "Mario's Pizza".
When the boy is playing Frogger, the high score at the top of the game console is 7,190, the boy's score from his just-finished game. A few seconds later, the high score at the top of the game console is 860,630 (George's ten year old score).
The guy whose last day was celebrated was at Elaine's return party 2 days later.
The store across the street from the pizza shop is first a florist shop, then a few seconds later, it is a cleaners.
When Elaine (Julia Louis-Dreyfus) is on the phone telling Jerry (Jerry Seinfeld) about missing her 4 o'clock sugar rush, the telephone cord switches from being under her arm to over.
The Frogger machine scores reset once power is lost. George (Jason Alexander) got the high score on Frogger while in high school. George and Jerry (Jerry Seinfeld) both attended John F. Kennedy High School, class of 1971. However, there was a city-wide blackout on July 13-14, 1977, at which time George's Frogger score would have been erased.
Regarding the "correction" on the power outage of 1977 wiping out the high score: Frogger wasn't invented until 1981, so this cannot be true.
George's initials couldn't have remained as the high score on the Frogger machine in "The Frogger" because arcade Frogger machines didn't store initials with high scores.
To get Frogger hooked up to battery power they would need to unplug the machine first. An alternative approach exists in which the machine could have been opened up while still plugged in. There is internal circuitry (a bridge rectifier) that converts AC to DC. Tapping in with the battery just beyond that point would make backup DC power available so that the AC power cord could then be safely unplugged.
The antique cake slice should have been nearly rock hard after all that time. Even if it remained frozen for 200 years it would still dry out and harden.
In the first scene at Mario's Pizza, when George and Jerry enter, the backdrop of the New York shops is reversed. The store name in the background is obviously backwards.
The Frogger Machine's high score are out of sequence and duplicated.
The outside shot of Mario's Pizza says Five Roses Pizza.
George orders two grape sodas. The soda dispenser offers only Pepsi, Mug root beer, regular Slice, orange slice and diet Pepsi. They are served their drinks in paper cups, not cans.
When Kramer and Elaine are at the counter at Monk's, the view through the front window is an obvious painting.
George greets the employee at Mario's Pizza as "Mario". However, the character's name is listed as "Sal" in the closing credits.
A large truck bears down on George while he's pushing the Frogger machine. Although we repeatedly hear the truck's horn sounding, the drivers hands never leave the steering wheel.
Jerry comments that Mario's Pizza was his and George's high school hangout. The pizza shop is in the city and Jerry and George went to high school on Long Island.
George (Jason Alexander) says his high score he achieved in high school was 10 years ago. The Andrea Doria (1996) reveals George to be 34, which would mean he was 24 when in high school.
Jerry brings a baseball bat to Lisi's place. Yet, when he leaves after dark, in fear of the lopper, he doesn't take the bat with him.
When Elaine (Julia Louis-Dreyfus) is on the phone to Jerry (Jerry Seinfeld) in her office, people singing "Happy Birthday" can be heard in the background. Moments later Peterman (John O'Hurley) says it was a "get well" party.
When Kramer's guys are playing Frogger on the machine that they are moving, they check the battery and calculate that they have three minutes before it dies. If they were able to power an AC-powered Frogger machine with a DC battery, they almost certainly would've known that they could've extended that time significantly by turning off nonessential components (especially the power-hungry cathode ray tube display, which is only necessary when the game is actually being played) rather than having to plug the Frogger machine in. This would reduce the machine's power and slow the drain on the battery.