In THE COMPLETE GERRY ANDERSON (and, I believe, the blurb on my DVD) it says that Father Unwin collapsed from sunstroke. (The book points out that the front page of a newspaper indicates that it's February 3, 1969, which is a very odd time for anyone to get sunstroke, at least in this hemisphere.) However, there is no mention of sunstroke in the episode. When Father Unwin starts showing signs of faintness, Mrs. Appleby wonders if it's the sun on the Father's bald patch, but that is the only mention made. If it had been sunstroke, Father Unwin should have been sent to the hospital, and the proper treatment would not have simply been a "nice long rest".
BTW, Mrs. Appleby's reaction when Father Unwin collapsed seemed a little restrained. You'd think that she would start shrieking for Matthew, rather than just quietly calling him to come and help her. I really don't think that her voice was any louder than when she was speaking to Father Unwin.
As dream sequences go, this was a pretty funny one. It made sense, after Father Unwin's argument with Mrs. Appleby about Gabriel, that his dream would focus on just what a great vehicle Gabriel is!
I loved the horror in the fighter pilot's voice as he reported to his superior: "It's...it's a Model T!" I also like how Matthew spoke in his "normal" voice for most of the sequence, but reverted to his Matthew the gardener voice when they met the lady gas attendant, who looked remarkably like Mrs. Appleby. I also enjoyed her comment that, while the Father was a nice man, she didn't think much of his navigator.
They did a great job with those "native" puppets, showing a lot of bare skin without exposing the ugly joints in the arms and legs. And it made perfect sense (as it always does in a dream!) that the natives would understand Father Unwin's gibberish.
After the airfight sequence, Father Unwin commented that he hoped that the pilot was all right (which he was). He seemed to forget that the other two pilots must have died in their head-on crash.
The man they were supposed to meet was called "Dr. Purple" (who turned out to be the Bishop). Was this a reference to the purple robes worn by higher ranking clergy? Or does that not apply to Church of England?
Why did Matthew force Father Unwin to awaken at the end? Wouldn't it be more sensible to let him sleep himself out?