https://forum.speeddemosarchive.com/post/jinx_ps1.html for the posts

Things Cronikeys found (in that post): -You can use a box to bypass the spinning wheel that opens a gate in level 1 -You can do a sort of "super jump" when a box collides with an enemy and you ground pound off the box -Some of the "bottomless pits" aren't programmed correctly so you can walk along the edges -You can walk on the edges of unflipped bridges to skip a few puzzles -You can jump off enemies as they're dying -You can trigger cutscenes while reading signs to get the sign's message permanently on the screen until you press the jump button

Things RingRush found:

• After exiting a level you can use the last item you equipped in the overworld.
• Hole of Despair acts differently than other items. For one, you can avoid slowdown when throwing it by attacking simultaneously, which doesn't seem to work with other projectiles. It also lets you do a lot of weird things:
• Throw a hole and interact with something (such that you don't need to move) simultaneous to gain control back. This has a lot of interesting consequences. For instance, you can activate the world clock and then slip in an area with the door closing while the cutscene plays. This has some uses in 100%. You can also walk around with the globe options up, which includes the ability to save anywhere, even as you are warping away to a level. This disables pausing in the next level and seems to create some severe graphical glitchiness when you try to load the file. Finally, if you do this on a level then move far away from the warp, you can get some weird effects where you just float oob without control. This can be used to get a position value (according to RAM Watch) behind the door to Buccaneria early, but you unfortunately have no control to take the warp. Get sucked up by a black hole just after confirming a warp to get sparkles surrounding you.
• Throw a hole beneath someone you want to talk to or a warp to get various amusing effects. This can be used to get control with text up on seemingly any source of text, which can lead to a lot of other buggy things. This might also be usable to replace a long conversation with a shorter one or potentially do some conversation skips. If you use the text at the start of the final level and choose to warp back to the hub, then game over, you can enjoy -1 life mode. Your next death will game over you. If you try to enter a level the game will softlock (unless it is a bonus stage in which case after timeout you will be softlocked) and seemingly randomly while walking around the overworld you can lose the ability to jump or use items or move up and down.
• Jumping just before taking damage lets you do a jump that looks to be about 1.5x as high as a normal jump. This can be done with grenades for high jumps on the go. Pulling up your inventory or pausing can be used to change momentum in weird ways...normally it brings you to a stop quicker but I've also noticed I go slightly farther after a damage boost if I pause at the right time before hand.
• To add to the above post you can jump off live enemies too, as well as NPCs. But invisible walls and ceilings galore in this game.