Amy Rose is the founder of a Sonic the Hedgehog "Fan Club", one of which has the admission fee of $5 to join. It has at least one member aside from Amy, a non-specific badger.
In the early days of the Archie comics, Antoine's hairdo was a wig. In the transition to a more serious story, this recurring gag was dropped and he grew out his hair.
In Sonic the Fighters, Bean the Dynamite is the only cpu character who can activate hyper mode. It's likely this played a part in determining his eccentric nature in the Archie Comics.
Dr. Starline appears to have recently broken this rule, as the Warp Topaz is implied to be something he found rather than invented. "A unique gemstone I've spent my career researching" suggests that he simply knows how to use it, rather than invented it.
However, in Sonic: Bad Guys #2, Dr. Starline does create the Tricore, albeit with Eggman's own tech.
Amy Rose seems to be the only character in the main Sonic the Hedgehog cast who can handle a casual punch from Knuckles.
Scott Pilgrim's high school band "Sonic & Knuckles" is a very subtle reference to the 1994 Sega Genesis game Sonic & Knuckles.
Sonic the Hedgehog does not know what hedgehogs look like.
Whisper the Wolf's design began with an in-game custom character in Sonic Forces. From there, she would gradually evolve into her final look.
Tails is very discontent with the fact that Eggman has settled on making Tails Doll rather than a Metal Tails. Moreover, this suggests that he finds Metal Sonic and Knuckles to be particularly cool.
When robots or lackeys fail, Eggman uses his built-in command grab
In 2015, it was revealed that Ian Flynn, Tracey Yardley!, and Ben Bates of Archie Sonic the Hedgehog fame had pitched a line of Super Mario comics to Nintendo. It was ultimately rejected. Allegedly, Mario was also intended to cross over with Sonic and Mega Man in comic form.
Knuckles the Echidna's father dies of pancreatic cancer in the Archie Comics.