Crash
As an airline captain, I would like to weigh in on the crash sequence:
1.) When the plane's wingtip hit the top of the oil rig, that could have taken the aircraft down, if the strike had been further inboard on the wing. With the plane going at its speed, and the wingtip hitting, it could have sent the plane into a potential flat spin, and down it goes. But, since it didn't, it would have to have been a graze that only took off the very tip of the wing.
2.) That being the case, I am not sure why the #4 engine caught on fire. Debris from the strike, maybe? Regardless, the depiction of the engine fire was VERY accurate. It caught on fire, he pulled the fire handle, which shuts everything on the engine down, then fired the extinguisher bottle on the engine. The extinguisher tried to put the fire out. When the fire reignited, he used the extinguisher off the #3 engine to try to put the fire out again.
3.) The plane should have been able to fly just fine, though. Three engines is more than enough to keep the plane in the air, and even gain altitude fairly easily. Two engines would have kept the plane in the air, and even allowed it to gain a modest amount of altitude. If the plane hadn't crashed in the first place, the wing damage would have to have been slight in the first place, which would have caused more drag, but not been catastrophic, by any means. But, the movie requires the plane to crash, which is the only reason it does crash.
4.) Albert Whitlock and his visual effects crew did an AMAZING job with the crash sequence. It is freakily on point! The tail striking would have jarred the plane as shown. The engine hitting would have been catastrophic, causing such a pull on the aircraft, that it would have brought it down, which it does. And, the visual effects are scarily realistic. Whitlock was always a great effects artist, famous for "Earthquake" and "The Hindenburg."