Take your pick: which is the most popular misconception? 
The Hindenburg blew up because it was filled with dangerous/flammable/explosive hydrogen (See 3.4)
The Hindenburg was designed for helium but the Americans would not sell it to the Germans who then were forced to use the dangerous/flammable/explosive hydrogen (See 3.1)
The Hindenburg made a tight turn, a wire broke, which cut a gas cell, (or maybe it was a leaky valve), hydrogen escaped, mixed with air, then the mix made a u-turn at the covering, then resisted dispersal and diffusion until the nose ropes grounded, which generating a spark at the other end under the cover near the oxy-hydrogen there, which caught fire and that ignited the covering. (See 3.5)
Just like in the movie, a mad bomber placed an explosive device timed to go off after the passengers disembarked and its firey blast ignited the dangerous/flammable/explosive pure hydrogen in the cells which then exploded spreading fire to the covering. (See 3.4)
Begin with 3.1. LZ-129 Evolves
Continue reading to 3.2. The US Navy and the Hindenburg
Continue reading to 3.3. Hindenburg Götterdämmerung
Continue reading to 3.4. Hindenburg “Explosion”
Finish up with 3.5. The Zeppelin Rebirth: Finding the Cause