There was definitely some dialogue permitting them to land over the radio.
I agree about Barton though, it would have been great to have Thor use some kind of cure on him like healing stones (cut from the Thor movie). Or even have Widow shoot him up with some kind of IV that would kick start the nerves in his brain or whatever movie explanation they could choose to do.
Outside of that, the only things that bugged me were 1. the half-assed explanation of how Thor got back to Earth, and 2. the Chitauri falling over dead when the mother ship was destroyed. They're living creatures, not battle droids. Maybe on the blu-ray we'll get a deleted scene saying the tech in their suits allow them to breath on Earth or something, so when that shuts down they die.