I am a huge fan of the movie Mad Max (not really the other Mad Max movies, just the original,) and I can’t understand why the famous poster for the film (also the VHS box cover) depicts Max wearing a helmet with a face shield. To my knowledge, he wears no such helmet in the entire movie. Was this just an oversight, or was he originally supposed to wear a helmet and the poster created before that was changed?
“Artistic License”.
There were no stars in the movie, so they couldn’t exploit a famous face. They had to sell the iconic image of Mad Max. That image would sell better if there weren’t a face attached. Fidelity to the movie has nothing to do with selling the product. Fidelity to anything never has anything to do with selling the product.
Film posters have always had a very tenuous connection to the film in question. For a famous example… Hammil and Fischer could only dream of ever having these torsoes..
Wait a minute…wasn’t Mel Gibson already an established star in Australia at that point?
According to his IMDb bio, no. He’d had three roles, on of them on TV, and one of them uncredited. Even if he was famous for those few roles, it’s additionally possible that the poster for Mad Max was different in Australia than it was in the US. The IMDB entry for the film does not feature the poster the OP talks about, but I’m not sure what the provenance of that poster is. It might be the original Australian poster, it might be the cover of a later release of the film, or something else entirely.
I think he did wear a motorcycle helmet in the first movie, when he was still a cop. I might be mis-remembering, but I seem to recall him wearing a helmet while riding his cycle.
Max never rode a motorcycle. He drove a police interceptor.
Did Max have a friend who was a motorcycle cop then? 
It has been years since I have seen the movie.
I remember the OPs link being the original poster/video box cover. The rights to the first movie must’ve been sold to some cheapie company 'cause you could find it on all the bargin tables with a really cheap cover (created to take advantage of Mel Gibson’s fame) during the 90’s.
Huh, looking at this incredibly complete Mad Max fan page, it appears I was correct. You can see the original cover (linked by the OP0 about half way down and towards to bottom of the page is the cheapie Good Times video release. There are also covers of the first two Australian releases, one of which uses the motorcycle helmet cover.
Goose.