It's another glitch, I've seen it several times. Isn't the one you're referring to related to background (plane B )? The one I'm talking about there is on the foreground (plane A). It happens when the lamppost's bottom (ie the coordinates used to respawn Sonic) is inside the ground's collision. Here's a pic: I guess it's a problem with plane A not being redrawn for a short time after respawning when Sonic is "pushed" out of the collision. The visual glitch will, of course, disappear once it's out of the screen.