When Diego walks around near the car outside the old warehouse in Monteverde, his cravat can be seen at the back and is clearly held together by Velcro rather than truly tied in front.
Llanos stole the wedding film in order to destroy evidence that he was skulking around the night Andres died, and everyone--including Inspector Ayala--views the evidence as lost. But the film production studio would still have the negatives and be able to produce a second copy.