This Is Why I Hate Machines

A space bridge accident sends Ratchet and Captain Fanzone to Cybertron, right as the Decepticon controlled Omega Supreme arrives.

Synopsis

(Numbers indicate order of appearance.)

Autobots	Decepticons	Humans
Ratchet (1) Sedan? (3) Freeway? (4) Carerra? (5) Huffer (6) Glyph (7) Hubcap (8) Bumper? (9) Powerglide (10) Grandus (11) Flareup (12) Steeljaw (13) Zaur (14) Sentinel Prime (15) Autotrooper (20) Ultra Magnus (21) Tracks (22) Jazz (23) Jetfire (24) Jetstorm (25) Omega Supreme (26) Perceptor (27) Alpha Trion (28) Rattletrap (29) Arcee (30)	Shockwave (16) Megatron (17) Lugnut (18) Starscream (19) Lockdown (31, flashback)	Captain Fanzone (2)

"I'd be a happy man if I never see another—[Fanzone takes in his surroundings]...robot?

—Captain Fanzone enters his own personal hell, and its name is Cybertron.

"I can't believe we're on Cybertron! Of all the places we transwarped, this is great!"

—Ratchet, happy for the first since...well, since we've seen him.

Shockwave's head model changes randomly throughout the episode in shape, size and positioning of his optic.
When Shockwave holds up the Magnus Hammer and starts generating lightning, its handle is only half as long as usual.

When Ratchet and Fanzone are headed to Maccadam's, they stop in front of a building which appears to have Target's trademark "bull's-eye" logo.

Parade footage from "Decepticon Air" is used in Sentinel's little propaganda video. (See said episode for the list of cameos within.)

Ratchet remarks that Lockdown was the one to capture the Decepticon prisoners, as seen in "Five Servos of Doom".

The Autobot Council's headquarters is known as "the Metroplex", and the Elite Guard's battle station is "Fortress Maximus".

Ratchet's flashback uses footage from "The Thrill of the Hunt", giving Lockdown a brief "appearance" in this episode.

At the end of the episode, Shockwave utilizes an electronic paint job to reveal his "true colors", represented by a Target exclusive redeco reminiscent of his Generation 1 namesake's color scheme.

Sentinel Prime's broadcast was based on The Red Scare during the Cold War. The broadcast concludes with him saying "I'm Sentinel Prime, and I approve of this message."—in the style of contemporary political campaign ads.
Sentinel's insistence that he is the one who "makes the tough decisions" and insistence that any questioning of his orders is tantamount to treason is probably some kind of statement about someone or something, but we'll leave it at that.
Shockwave's slow, deadpan delivery of "I'm afraid I can't let you do that" is a reference to the menacing supercomputer HAL from Stanley Kubrick's 2001: A Space Odyssey, who also featured an unblinking single red eye.