a news reporter named Hector Ramirez appears in G.I. Joe, Transformers, Inhumanoids and Jem, possibly implying that all the cartoons take place in the same universe. (1985)
Wheeljack's ears usually light up blue when he talks, but on occasion they're orange. (1984)
Brawn the dumbass doesn't notice Laserbeak sitting on his shoulder. (1984)
this Peruvian girl from the G1 episode "Fire on the Mountain" has the honour of being the first female character to have a speaking role in the cartoon. (1984)
Galvatron and Soundwave hold hands while flying. (1986)
the Combaticons form a robot pyramid. (1986)
the Combaticons (all of them) drive down the world's largest street. (1986)
Spike is allowed do work on an oil rig despite being a literal teenager. (1984)
according to Teletraan 1, Rumble is red. (1984)
The name of the Decepticon ship that eventually became their undersea headquarters went nameless for 25 years. It was retroactively called the Victory in the Transformers: The Complete Ark reference book.
More Than Meets The Eye pt 3 very briefly animated Optimus with exaggerated, 'puffy' proportions. This was due to mecha designer Masami Ōbari being contracted to work on parts of the episode, with his signature artstyle seeping in. (1984)
Starscream's slingshot. (1984)
the pilot episodes of the G1 cartoon have all the Autobots be able to fly, which was subsequently dropped in the series proper. (1984)
The Decepto-Pack, a plastic dress up set for children. (1985)
when the the first episode of Prime was re-aired, the Autobot symbol in the Bots' base was changed from the live-action movie one to the classic one. (2011)
Ratchet is absolutely flabbergasted by Wheeljack's shit. (1985)
Scavenger kills Prowl in a single shot. (1986)
According to Vector Prime, every single animation error you saw in the G1 cartoon was the result of a time-space anomaly. (2015)
Skywarp killed half the population of Beijing. Or at least, he claimed to. (2009)
Cy-Kill gets killed by Megatron in the gladiatorial arena. (2007)
Prowl flips a lot of tables. (2012-2017)
For reasons not yet known, rapid photodegradation (yellowing) in Transformers toys has become very common as of the last few years. Figures have been reported visibly yellowed while still packaged and newly-arrived on store shelves. (2021- )
an episode of Beast Machines shows shows a statue of Optimus Prime holding two Golden Disks. Writer Bob Skir suggested that they were either the disks from the Voyager 1 and 2 probes, or that Optimus won them in the 2,395,989th Annual Cybertronian spelling bee. (1999)
a power-up form for Prime Soundwave, as seen in an official Japanese Arms Micron promo video. This form requires one to purchase yogurt bottles and a plastic fork, as well as several other Arms Microns, and attach it to the deluxe Soundwave figure. (2012)
Tigatron dreams of almost every female Transformer in the multiverse appearing to fight over him. (2015)