Sonic & Knuckles is an unauthorized sequel.
Amy could have been playable in these titlesShe was meant to be playable in Sonic CD
Sonic's modern look and powers are side effects of turning Hyper Sonic.As Hyper Sonic, his eyes turned green, just like his modern look. Sonic 4, taking place after this, is the first canon appearance of the modern look and the homing attack. The biggest evidence is that as Hyper Sonic, he could unleash a double jump attack the propelled him further and destroyed any minor enemies on screen, and with the general ability to direct his momentum, and now the boosting he's clearly growing in power.
The asteroids in the Doomsday Zone are chunks of earth and pieces of the Sky Sanctuary that the Death Egg kicked up during its ascent.How else does one explain asteroids in orbit above the earth?
In the Special Stages everytime you do the Orb Turns Into Rings thing someone is getting hit and losing rings.Exactly what it says on the tin
Robotnik/Eggman himself designed the games and sets himself up for you to beat himI've read that Robotnik/Eggman has an I.Q. of 300, and while still prone to mistakes or oversights, it seems odd to me that Sonic can defeat him relatively easy. This puzzled me as it's fairly obvious that he knows Sonic's weaknesses. He knows that Sonic can drown/be poisoned (Chemical plant). He knows that Sonic needs rings (Death egg zone in Sonic 2) and he even knows about the 10 minute clock (Death Egg Zone 2 in Sonic and Knuckles, a lot of the transport hoops take a long complicated path that does nothing but waste time) So if he really wants Sonic dead, why not just set up a boss room that floods with poisonous chemicals, with no way out? Or trap him in a room for 10 minutes? Or have him fall into a boss room with an all spiky floor, that he can't jump out of, sort of like a certain pit in the Mystic Cave zone? Gameplay and story segregation aside, I think it's because Robotnik/Eggman knows that if he wins, things will get very boring very fast. A man with an I.Q. of 300 is likely a man who gets bored easily, and so when Sonic came along, someone who actually presented a challenge, he set things up to play a game with the blue hedgehog, complete with powerups of his own design (item boxes, shields, maybe even the rings themselves), and enemies, then waits and sees how well Sonic fares. Then he fights Sonic himself in a machine that has a built in weakness, and it's up to Sonic to exploit it. Why else are the item boxes, which are clearly technology, there? It's even more obvious when you run across item boxes with Eggman's face on them, and opening those hurts you. Or the betting machines in the Casino night zone, or the fact that even Robotnik/Eggman's bases are pretty hedgehog friendly, what with Sonic sized tubes, and devices that Sonic can operate, or if you take Sonic CD into account, the fact that all the bad future levels are run down, even Robotnik/Eggman's bases. Without you, he no longer has a reason to keep them in good condition.