Proto:Sonic the Hedgehog 3 - The Cutting Room Floor

Sonic 3 Prototype With Lost Content Discovered - SEGA Online Emulator

Sonic R [Prototype/Beta - Saturn] - Unseen64

Sonic Adventure Cutting Room Floor - Colaboratory

Sonic the Hedgehog (1991) prototype discovered, Page 2

Sonic the Hedgehog / Awesome Music - TV Tropes

Proto:Sonic & Knuckles/Sonic 3C 0408 - The Cutting Room Floor

The 1990 Tokyo Toy Show and beyond — unearthing new Sonic the Hedgehog pre-release evidence – MegaBites

Prerelease:Sonic the Hedgehog 3/Concept Art - The Cutting Room Floor

Sonic the Hedgehog 2 (2013), Sonic Wiki Zone

Sonic the Hedgehog (Prototype) LOST BITS Altered & Unused Content [TetraBitGaming]

Sonic 2 [Beta / Proto / Unused Stages - Mega Drive / Genesis] - Unseen64

Proto:Sonic the Hedgehog 3/Stage Differences - The Cutting Room Floor

Bugs:Proto:Sonic the Hedgehog 3 - The Cutting Room Floor