Complex sentence: The movie premiere will attempt to break the Guinness World Record for the largest attendance at a film screening, which is held by the premiere of 2012 documentary film Honor Flight with an attendance of 28,442 people.
Split into simpler sentences: The movie premiere will attempt to break the record of largest attendance at a film screening from the Guinness World Records. Currently, the record holder of latter is the 2012 documentary film Honor Flight with an attendance of 28,442 people.