Cliffjumper and Mirage share a moment.(1985)
Cosmos and Powerglide chase Starscream through the world's largest shopping mall. (1985)
Megatron is defeated by a can of spray paint. (1985)
Starscream admits that he is stupid. (1985)
Chris Latta's Starscream voice noticeably takes on a much higher pitch over the course of the series. (1984-1985)
due to the episodes being done by two different studios, the damage Optimus Prime incurred at the end of "Dark Awakening" is myteriously gone in "Return of Optimus Prime". (1987)
a billboard for Transformers: The Movie appears in the G1 episode "Make Tracks" (1985)
Ravage's one line of dialogue in the original series. (1984)
The model sheet of the Decepticon symbol created for the G1 cartoon is based on the one that appears on the toys' packaging. The animators misinterpreted the beveled detailing on the Decepticon symbol's crest, as a third spike on the crest. (1984-1987)
Optimus attempts to explain where his trailer goes when he transforms. (2008)
the Predacons attempt to dress up as Autobots to confuse the Decepticons, only to end up all dressing as Optimus Prime. (2001)
the Lost Light crew dress up as MLP characters. (2021)
Optimus defeats Cthulhu. (2012)
Takara releaes the Device Label line of Transformers, who all turn into fully-functioning computer peripherals and accessories. (2009)
concept art sketches for an Animated version of Bludgeon, reimagined as a pirate. Contrary to popular belief, this was not meant for the 4th season, and was mostly done for fun. (2010)
Concept illustrations for the season 4 Animated Autobot lineup, modifying the character designs with influences from the live-action movies. (2010)
TFNation 2019 held a live reading of the proposed premiere of Animated Season 4, "Trial Of Megatron", with most of the show's voice cast reprising their roles. Artist Eric Siebenaler also drew concept art of new characters Uplink and Trac-Tor, who would have appeared in the ep.
proof-of-concept pilot for Animated, produced to convince the network to pick up the show. It has never been publicly released, and was screened by Marty Isenberg exclusively for TFCon. (credit to @KeyanCarlile for the video)
Derrick Wyatt discusses an unmade episode of Animated that would have featured Optimus Primal. (credit to @KeyanCarlile for the video)
Super Cross, the original planned sequel to Armada. it would have involved Unicron abducting and mutating Transformers from across the multiverse, including characters from G1 and Beast Wars, to fight within his body so that he could absorb the sparks of the victors. (2002)
An extended version of the 2007 movie, containing two minutes of extra footage, was released to IMAX theatres. The footage has never been made available elsewhere. (2007)
Shockwave makes a blink-and-you'll-miss-it cameo on a newspaper in Revenge Of The Fallen. (2009)
the G1 episode 'Hoist Goes Hollywood' misspells Tracks' name as 'Trucks'. it's unknown if this was a legit spelling error or an extension of the running gag from the episode where the director constantly gets Hoist's name wrong. (1985)
Animated Sky-Byte has three different designs: the 'official' one from the Stunti-Con Job, another from the Allspark Almanac 2, and a concept sketch done by Derrick Wyatt. (2010)
Sentinel Prime's role in Animated was going to be filled in by Rodimus at first, before Hasbro vetoed the idea, not wanting Rodimus to be portrayed as a massive jerk. (2008)