Spoiler alert: This article contains plot information on the live episode of Thursday's 30 Rock.

The cast of 30 Rock went into live mode for a second time in series history on Thursday, and they did it with the help of a slew of guest stars.

The live episode, which was orchestrated again three hours later for West Coast viewers, began with a bang, and without its usual glossy, dreamlike layer that graces 30 Rock each week.

Live from Studio 6H begins in Jack Donaghy's (Alec Baldwin) office, as he breaks the news to Liz Lemon (Tina Fey) that TGS will now be filmed ahead of time instead of shot live.

Do you really love the overzealous studio audience who applaud at anything, here in the greatest city on earth, New York, baby, what's up! Jack says, to which the real NBC studio audience erupts in a roaring applause.

He goes on to say that the entire season of TGS will now be shot in two weeks, like 'Wheel of Fortune' and 'Fox News.'

When Liz protests against the idea and has a flashback to her childhood days of watching telethons in her parents' basement, we get our first (of many) guest stars: Amy Poehler as a young Liz Lemon.

From there, the live show goes uphill, as the next guest star, Sir Paul McCartney, enters Jack's office to use the bathroom (not before giving Jack a friendly slap on the face).

After the show's opening credits, performed once again by Jane Krakowski, her character Jenna announces that she's getting married to her cross-dressing boyfriend Paul (Will Forte).

If Jenna Maroney is getting engaged, it's gonna be on live TV. I've been working on my reaction since I was three . . .it's happening Liz, she tells Liz.

Moments later, Kenneth (Jack McBrayer) decides to take charge and locks most of the show's staff in Tracy's (Tracy Morgan) room. In a protest against TGS being filmed, Kenneth takes everyone down memory lane and revisits some of the network's most beloved live shows.

The Kenneth-narrated trip includes a tribute to real-life classics like The Honeymooners and Dean Martin's 1960s variety show, all acted out by members of the 30 Rock/TGS crew.

And Jon Hamm -- who plays an African American sidekick in a spoof of Amos 'n' Andy.

NBC had the first two black characters on TV. Sort of. For 'Alfie 'n' Abner', NBC hired one African American and one Caucasian because they thought two black people on the same show would make the audience nervous -- a rule NBC still uses today, Kenneth explains before the flashback.

Hamm later returns in the live episode to portray a newscaster in another flashback parody of an NBC News Special Report, opposite Baldwin.

Viewers on the West Coast however, only received one dose of Hamm on Thursday, as he was replaced by Brian Williams in the news desk skit). Kim Kardashian also replaced McCartney in the show's opening bathroom bit. And the show's opening theme was delivered by Cheyenne Jackson, who gave viewers an update on the NFL draft.

Jimmy Fallon, Fred Armisen and Donald Glover also made appearances as a young Jack Donaghy, a telethon volunteer and a young Tracy Jordan, respectively.

And if having Jon Hamm guest star twice (on the East Coast episode) wasn't enough to show how much the 30 Rock family loves Mad Men, the show delivered its own rendition of Zou Bisou Bisou, the same French tune actress Jessica Pare belted out as Megan Draper show's season premiere a few weeks back.

The next (taped) episode of 30 Rock airs next Thursday, May 3.

Scroll down for highlights from last night's live show.