This is from what I remember, I may easily be a bit mixed up so like I said; best to search for yourself (and correct me if I'm wrong);
There are different versions of the game out there. Initial versions of the game were released with a couple of levels bugged; the most game breaking was Tanks a lot and My Finest Moment* They (the creators) released a new version which fixed this (was apparently just a patch, not all that unlike the patches GuyPerfect and ccx created.
Unlike any other Lemmings game that I'm aware; each level of this game has it's own unique deadly fall height. While they don't differ greatly; if you're really observant you can tell on a few levels where it's noticeably shorter and some where it's noticeably taller. I can't remember which levels but one in particular it's super short in place I don't think matters much anyway...
*and* on top of this; unlike any other Lemmings game, the difference in height doesn't go from survive to splat; there's at least 1 pixel/space (I think it's just one) where there's an essentially 50-50 chance of death. This is why when playing Tanks a Lot on the broken version some Lems may survive while most die. There is a spot left of the upper entrance on the level "Just you wait" that is this exact height (no patch for this level) which isn't nessecary to use to solve the level but you can use it; but if you do you have to keep trying until you get a lemming down there safely.
Anyways; the "patched" version essentially just increased the safe fall height distance in said levels (and nothing else).
I don't know about a fall height issue with The High Dive. My only issue with that level was the game crashed when trying to load it. I know this doesn't have anything to do with the official patched version because I have that version (never had any issues with Tanks a Lot) and I had the High Dive issue. My game also only crashed under certain circumstances, but I don't know what those were. The High Dive glitch never happened on win98 or winXP and only happened after some point I used it on Windows7. I'm sorry I can't remember when/why this occurred and what we did to fix it.
*I think there is a alternate solution to My Finest Moment that can get around the glitch but don't ask me to remember it.
Look up "pirohiko" on youtube for solutions to all the levels; including alternate solution to My Finest Moment.