Heartwarming / Sonic 3 & Knuckles

• If you complete Sonic 3 & Knuckles with all Super Emeralds as Sonic and/or Tails, a short scene is shown on a restored Angel Island Zone — after the Floating Island rises, Knuckles runs past the Master Emerald to see them off.
• Likewise, completing Knuckles' story with all the Super Emeralds will yield a triumphant victory — even as the Floating Island wobbles in the sky uncertainly as the last vestiges of the Sky Sanctuary collapse with the crumbling remains of Mecha Sonic, Sonic catches Knuckles with the Tornado, and the echidna has managed to recover the Master Emerald. He flashes a good-natured thumbs-up at Sonic, then they fly back to the Floating Island, returning the Master Emerald and restoring the Island's ability to fly.
• The three finally teaming up after Knuckles realises he's been duped.
  • An easily miss-able one, but in Sky Sanctuary Zone as Sonic and/or Tails, Knuckles will jump onto an activation switch and you'll have to leave him there. Positioning exactly the right place beside him and looking down (which might be Sonic bowing to Knuckles, given the game's Japanese dev team) will lead Knuckles to point forward as if to say, "I'm fine, go on without me!"
  • Also, when Sonic and Tails encounter Knuckles in the first two zones, Angel Island and Hydrocity, he presses a button making the bridge below them disappear. Here, after being beaten and learning the truth, he uses the last of his energy to press a button making a bridge appear for them.