In the Archie comics, Nack had a trio of other hitman weasels named Jeff, Karl, and Konor. After a failed murder attempt of Sally, Nack ran off and his crew was arrested. Sometime later, Nack would poison the food of his gang, killing them and giving him a confirmed body count.
For the Sonic Adventure adaptation, Archie went through some stories to explain how characters took on their then-new designs. Amy had wished on the Ring of Acorns to become older to join the Freedom Fighters and get closer to marrying Sonic. ...She's still mentally a kid.
I'm not interested in any legal discussions being had about Amy's character here, but I will simply say that as an 11 year old girl in a 17 year old's body (pre-SGW), she has mentally matured over the years. That's nice at least.
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.
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.