After reaching the helicopter it is clear that it only has three seats. Somehow they manage to fit 4 people into the helicopter.
David and June both get down on the ground and roll underneath the low rail of a board fence causing them both to crawl in the dirt in order to get under the fence rail. However when they get up neither David's jacket and slacks or June's skirt or the dark colored jacket she is wearing appear to have any dirt on them at all.
A group of Invaders hear a guard outside fire his pistol - despite it having a silencer.
On the ranch all of the alien's carry rifles and revolvers fitted with silencers even though they are in an isolated rural area. There would be no need for silencers in this type of location.
Once in the helicopter Jeremy Mace takes the controls and expertly flies the helicopter without the least hesitation. Prior to this there is no indication that Jeremy is capable of piloting a helicopter. Even when Jeremy, David and June are discussing their plan for Jeremy to get the gun from the guard and take Eric Lund hostage after which they would escape in the helicopter.