The Union Jack which Peter and his pirates fly before hoisting the skull and crossbones is flown back to front. A common mistake. In addition, Shelly Boothbishop calls it "the British flag". A British person would more likely call it a Union Jack.
Peter's pirate gun does not recoil. Since it is not tied down, it should recoil all over his merry gang of pirates and crush them.
When Peter and Shelley Boothbishop are fencing between the cars and as the shot tightens in, the mask for the steering wheel in Peter's car is out of position and reveals the buildings moving behind the car.
When Peter and Shelley Boothbishop are fencing between the cars, Shelley's hand doesn't move on the steering wheel when the cars dart back and forth, while Peter's hand does.