When Billy looks up at the sky and identifies an F-17 as a Tigershark. The "Tigershark" refers to the F-20 designed and built by Northrop Corporation during the 1980s but was not adopted by any of the US military forces. With respect to the F-20, it was a single-engine jet aircraft and likely would not have left twin contrails.
There never has been an F-17. At one point, there was a YF-17, which by its designation was an experimental aircraft. Eventually, that aircraft became the F/A-18.
When Billy is hit by the police car and is airborne, he sees an aircraft that he identifies as a P-38 Lightning. The aircraft in question was used during WWII. It was a twin piston-engine, propeller-driven, multirole fighter-bomber. Again, the twin contrails shown would have been unlikely to have formed.
Before Dean unlocks the door to Troy's apartment, there's a shot where you see Dean from inside Troy's apartment. In that shot, you can see the gap between the door and the door frame that the deadbolt is not locked. You can also see the thumbscrew on the door knob is in the typical unlocked position. But Troy gets a hidden key to unlock a door that's not locked.