Using wayback machine can browse a fanpage that held glitches, on this page you'll find text descriptions with screenshots. The authors of the glitch submissions highlight what versions of the game the glitch is possible on along with the difficulty of execution: https://web.archive.org/web/20180704160225/http://web8.orcaserver.de/ecco/glitches/

There are also video demonstrations of said glitches found here: https://www.youtube.com/playlist?list=PL033D5DD66BC3F9BE

With the recent interest in DotF as of spring 2020, new glitches have been discovered (all only tested on PAL/NTSC-U Dreamcast). A YouTube channel has them all to view with small explanations in each video's description, if you seek help with these newer glitches don't hesitate to reach out to me or @DudeMcBro: https://www.youtube.com/channel/UCyPgBivFRleK6qG_8mX45wg/videos