Oh, pshaw, the details don’t matter - it’s a show about nothing anyway. 
It did have the right thematic elements, yes?? George in the restaurant with the guys, they were offering the pie, but George didn’t want to take any (because he suspected the chef had done something to it,) but didn’t want to explain why either.
And though George lost the job, the guys who had eaten the pie really were sick IIRC. Is that true too?
EDITED: Annie, yeah, that’s the one I started with, apparently. 
You were doing great up until here.
That wasn’t Kinney. But she was in the one where the guys parked in a handicap spot.
Bull. You got it wrong and now you have to become my butler.
Another ‘before she was famous’ sighting on ‘Seinfeld’ - Wendy Malick, famous (arguably) for playing Nina on ‘Just Shoot Me’ was the chiropractor with terrible hair.
Caroline Leifer, a comedian who was already famous (and whom Jerry Seinfeld dated dated in real life, and is supposedly the RL inspiration for Elaine) played Malick’s secretary.
On the side topic of how ‘Seinfeld’ is slightly dated, there is an episode when Elaine has her phone # changed to a ‘646’ area code and nobody wants to call her anymore because no-one wants to dial the extra numbers on the phone. These days virtually everybody in NYC has a cell-phone with speed dial.
I believe she was also a writer on the show.
I didn’t think it was the extra numbers so much as everyone thought she didn’t live in NYC because she didn’t have a “212” area code? I seem to remember her getting hit on and giving the guy her number, and him saying something like “Oh, I don’t do long-distance relationships.” I think that’s what finally got her to change her area code back.
JERRY: So you didn’t get the job.
GEORGE: No. But I was the only one at the table that didn’t get violently ill.
I thought she was also his manager.
And in the pie one, the team almost didn’t want to hire George because the suit he wanted so badly made a SHHHH noise when he walked.
Top o’ the Muffin to You! And Elaine wonders if they really need the exclamation point.
Deborah Jo Rupp played Jerry’s manager. She later played Phoebe’s sister-in-law on Friends and Eric Foreman’s mother Kitty on That 70’s Show.
I loved her role! She arranged gigs for him and exhaustively filled him in on every detail, including hinting about when he should go to the bathroom.
I feel like I’ve seen the guys who played the Bizarro world Jerry and Kramer elsewhere, especially the Kramer, with his flattop.
Not true, this was all just a product of George’s neurosis.
(everybody’s laughing at the table)
MACKENZIE: You taught I’d care about your pants wooshing?
GEORGE: I heard the last guy got fired because his nose whislted.
MACKENZIE: No, no, no. He got fired because he wasn’t a team player. That’s something we don’t joke about at MacKenzie. You’ll find we’re team here George. We don’t tolerate dissent. If you want to go your own way, you’re in the wrong place.
GEORGE: No problem there. Conformity is an obsession with me.
(The waiter brings dessert) *
Working backwards from the bit-players-who-went-on-to-other-sitcom-success story, sometimes when I see Jerry’s mom I still want to ask her if she’s had any ALF (aka Gordon Shumway) sightings lately!
And…one of George’s bosses (Kruger) was Commandant Spangler on Malcolm in the Middle.
Just noticed that the cab driver from The Puerto Rican Day episode is, in fact, Charlie Utter from Deadwood. No beard, though.
The show really is packed with people who went on to more recognizable roles. . . but how about the reverse, actors who were long off your radar but then popped up in a Seinfeld? I remember how pleased I was to see Gordon Jump, formerly of *WKRP in Cincinatti * and many Maytag commercials, pop up as George’s boss at Play Now, Mr. Thomassulo.
Thomassoulo: George, I realize we’ve signed a one-year contract with you, but at this point I think it’s best that we both go our separate ways.
George: I don’t understand.
Thomassoulo: We don’t like you and we want you to leave.
George: Clearer. . .
Jerry Stiller got a whole new career going when he played George’s father and later Carrie’s father on the King of Queens.
I guess it’s all on how you look at it… Wendy Malick was Martin Tupper’s ex wife on the HBO series Dream On. I’ve been a fan of hers for a long time.
The first time I saw Wendy Malick was yeears ago as an abused wife on L.A. Law. My memory is that she was so good I had a hard time seeing her in comedic roles!
To be honest, I was kind of hoping that this thread would have more observations besides the famous people/character spottings. Yeah, I know, I did use that as my example in the OP!
The Apple/Mac progression is definitely a good one. Not really something you’d notice when the show was on the air, but easy to spot now since they’re all antiquated by today’s standards.
I like that the actor who played Uncle Leo played in The Outlaw Josey Wales as the hillbilly bounty hunter who corners Clint Eastwood in the swamp. After the two bounty hunters are dead, Clint’s companion says,
“Wish we could bury them.” To which Clint replies,
“To hell with them fellows. Buzzars gotta eat same as worms.”
And spits a stream of tobacco juice on Uncle Leo’s head.
I also like to track who played themselves. Here’s a start:
Keith Hernandez
Bette Midler
Jon (not John) Voight
Feel free to add any others.