Flying Battery Zone Act 1. The loop point in the "echo" track of the lead instrument is set slightly later than the rest of the tracks; as a result, it falls further and further out of sync every time the song loops. This was fixed in Sonic & Knuckles and its lock-on. For some reason, this version of the song was used in Sonic Origins, but since the audio was converted to a streamed format, the desync isn't as noticeable.
