This is just voodoo myth making, it shouldn't be a part of any discussion about the correct way to load an M5. The OP and yourself have your own problems, but don't add into the paranoia. I mean, it's strange how you just did this and it slipped but presumably beforehand it didn't? The tongue of the film has nothing to do with anything, unless you are cack-handed and just get something wrong, but how you do that is a mystery in itself.
Well, It's unfortunate that you found my report to be "voodoo myth making," but it's a free country so you're welcome to make that judgment. Perhaps my experience will help someone else.
This is an old post but here was my problem. I was leaving the bottom rewind crank extended so as to be ready to backwind the film to snug it up. Turns out that activates/deactivates a clutch. If you fold the crank handle back in place (flush) problem with mis-loads ended.
One point not mentioned. The OP states that after loading film into M5 and fitting base plate, he backwinds film into cassette to reduce tension. He could be forcing film off tulip. I just wind forward and make sure rewind knob turns by itself. Sometimes we try too hard “making sure”.
This is an old post but here was my problem. I was leaving the bottom rewind crank extended so as to be ready to backwind the film to snug it up. Turns out that activates/deactivates a clutch. If you fold the crank handle back in place (flush) problem with mis-loads ended.