A lemming was allowed to fall 60 pixels before he splatted. Any other number, and it was a hacked copy.
There was never any editor released, so any version with an editor is also a hacked copy.
On frame 1 of the explosion (when the background is removed, and the lemming starts to fly apart), the blocker collision is removed. Windows Lemmings was a "C" rewrite, so it might have bugs/new features in it that were missed. Its fairly simple to convert 68000 into x86, but when coding into a high level language, you sometimes miss bits.
This is the Amiga (and probably the PC DOS) behavior. The PC version was a line for line (virtually) conversion of the Amiga one.
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