It's possible that 3 (NTSC-U) and 3 (PAL) have different physics, I need to test this. It's also possible they have different timing, and I'm not exactly sure how I'll confirm this.
3 (NTSC-J) has some significant differences, including POTENTIALLY physics changes (source: reddit so need to check)
3 Special Edition (PAL) has very different physics and even craft stat changes over 3 (NTSC-U). Testing it just now, I think they also did a major nerf to the amount of damage wall collisions do.
Gonna have to burn some CDRs today.
Upon review, I wonder why they did this much tweaking? Like they very obviously were still patching and updating the code from NTSC-U > NTSC-J > SE, not just bugfixes but pretty noticeable changes. Part of me wonders if this is because they thought it'd be the last wipeout they worked on? Fusion was a mess and I believe made by a different team than the PS1 folk. Citation needed.