Complex sentence: According to a "Making Of" documentary, producer Deeley was unsatisfied with the four endings written and conceived the current ending as a (literal) cliffhanger appropriate to an action film which left an opportunity for a sequel.
Split into simpler sentences: According to a "Making Of" documentary, the film's ending was the brainchild of producer Deeley. He was unsatisfied with all of the four endings written at the time and conceived the film's current ending as a (literal) cliffhanger appropriate to an action film which also left open an opportunity for a sequel.