Factual error: Helicopter rotor blades do not unfold by themselves and there is no way to unfold them from inside the helicopter. A trained mechanic with the right tools and equipment (including the proper ladder for the job) will take a minimum of twenty minutes to rig a four bladed rotor, and that's if (s)he's in a hurry. An airborne (i.e. falling) helicopter? Forget it.
Factual error: When Madison falls through the stage floor she breaks a pipe and her pistol ignites a flame. I'm guessing this must have been a natural gas pipe, which if broken leaves no regulation of the natural gas flow, therefore the explosion would have taken out the entire stage not just sent a little flame coming up through the hole in the stage.
Factual error: In the scene where the helicopter falls off the bridge there isn't enough time to start the helicopter, let the systems get enough pressure and get the blades rotating fast enough to provide enough lift to fly plus at the angle the helicopter was falling it couldn't even auto rotate.
Factual error: When Lucy L. is using the gas pipe as a flamethrower, it is suddenly turned off afterward. This could be because of one of the other characters turning the handle, but if they turned it off in that way (or any way), the flame would go inside the tube and make the tank blow up.