Hang on for this one.
When we first see Lois Lane, she is on a Boeing 777 with other press, covering a Shuttle launch. It's a new design, with the Shuttle Orbiter strapped on top of the plane from which it will launch. A glitch messes up the launch routine, and the Orbiter cannot disengage. It launches still attached, pulling the plane along with it. Superman comes along, zaps the restraints with heat vision, and flies the Orbiter to safety. However, the Orbiter engines have burned off the tail of the plane, which is now spinning down to Earth. Superman grabs a wing, which rips off. The other wing tears off, and he is only barely able to stop the plane from hitting the ground by flying in front, and pushing up on the nose.
Well, yikes. OK, first, why would NASA put press on the plane underneath a launching Shuttle? I know NASA has made some bad decisions, but that's a doozy.
Second, you just can't launch a Shuttle Orbiter that way! It takes a vast amount of fuel to lift something as heavy as an Orbiter into space. The two solid rocket boosters on the real Shuttle are needed to get it off the ground. That giant orange tank? That carries the fuel for the Orbiter to burn on the way up. Did I mention it takes a lot of fuel to get the Orbiter up? That tank is big. Giving the benefit of the doubt to the movie, maybe there is some new kind of fuel used. We do see black smoke from the Orbiter in the movie, when in real life the flame from the Orbiter is blue, with no smoke. I'll note, though, that black smoke in a burn sequence usually means a very low efficiency burn; the burning is incomplete and you don't get nearly as much thrust. But maybe I'm reading too much into a dumb movie sub-sub plot.
But could a Boeing 777 carry a fully-fueled Shuttle Orbiter? Sure, you've seen images of the Orbiter on top of a plane, but that's when they land it in California and it gets returned to Florida. The Shuttle is empty, without fuel. So let's see:
The dry weight of the Orbiter is about 170,000 pounds. With fuel it weighs about 254,000 pounds. A 777 airplane has a max takeoff weight of 632,000 pounds, and a dry weight of 314,000 pounds. That means it actually could carry an Orbiter (254,000 + 314,000 = 568,000 pounds, less than the max weight of 632,000 pounds). I'm surprised, but that part of the movie is correct!
But you still can't launch it that way. It would destroy the plane with its exhaust, even if it weren't still attached when the engines ignite. But attached it was. The thrust from the engines would have torn the top right off the plane.
Third, grabbing the wing of the plane was a dumb idea, and the movie got it right. It cannot support the weight of the plane (at least, not when it's torqued like that!), and it tore off. The other wing tore off due to air resistance, which was also correct. But before you think the movie got all this right, remember, he stopped the plane by pushing up on the nose, slowing it. I don't think the nose of the plane can support that much pressure! In the movie, you see the metal of the fuselage crumple a little, but I think instead Superman would have pushed a hole right through the plane. A better idea would have been to punch through the outer skin of the plane and grabbing the frame underneath. That would have been just as cool. I have to say, though, that this scene was maybe the most exciting in the movie, and very fun to watch! But still-- I hate forced coincidences in movies. Good thing Superman returns on the same day Lois would have been killed if he were still away. Feh.