Ah, thanks for the tip. I wouldn't have looked there since it's in French and everything.
I took a quick look at it and perhaps it's not much exciting but still a good milestone in Lemmings stuff to note. A few things I noticed:
-Indeed the "unused" loading screen is used. In the disk files it is available as a stand-alone file, but I can only read it in Workbench. not in Windows. I imagine it's a DPaint formatted file or something and that's why.
-The "out" counter is always 3 digits, in the final it changes based on how many digits the actual number of Lemmings out has.
-The game is one of few words. It just says "Well done, target reached" when you beat a level (and then automatically proceeds to the next level) and "Not enough I'm afraid" if you don't. Percentages here are displayed similarly to that out counter, always in 3 digits with extra spaces padded with 0s.
-No sounds when Lemmings drown. (However, this seems to be intentional-- the message you get at the end of the game promotes "full blown sound effects that are not in this demo")
-More than 100 lemmings! "Watch Out, There's Traps About" has 120.
-I don't remember if this is true for the final or not, but the exit in "If At First You Don't Succeed" is mispositioned two pixels too low.
-I also don't remember if this applies to the final or not, but the samples used in the music are stand-alone files on the disk.
