Transformers
In the film, Sam puts a pair of glasses up on eBay. He had no idea that these were the same glasses that the Decepticons are looking for. We later learn that the Decepticons know how to hack the US military network, so couldn't they have just hacked the bid? Maybe eBay didn't want to promote hacking on their site...
The Lost World: Jurassic Park
In the film, the T-rex's boat crashed into the harbor. It then escaped and quickly killed everyone on board. Truthfully, this was too easy. There's no way a giant dino like that one could have killed so many people with ease in such a tricky situation!