One of the searchers speaks of looking more for Steve the next day, "when it gets daylight", but the sky is clearly a bright blue, indicating that it is actually the middle of the day, and the film is just underexposed to simulate the dimmer illumination of twilight.
When Steve pulls off the door of the truck, you can see the wire attached to the door to help it go flying.
When Steve jumps off the truck, it is obviously a stuntman rolling down the dirt hill: his hair is very blond (much lighter than Lee's) and his face isn't fully concealed from view.
Footage of the crowd watching Steve argue and then fight with the bad guys is quite fuzzy and its lower resolution makes it appear to be either stock footage or shot with video instead of film.
Around the 32min mark when Steve is having a brawl with the local guys from town, you see Steve throw one of the guys over the cart that is filled with hay, you can clearly see the wire pulling the guy backwards over the hay cart through the air.
When Steve Austin remembers Oscar Goldman in flashback, we see footage of him from the next episode to be broadcast, The Peeping Blonde.
Assuming the global coordinates for the location of Steve's crashed plane are given in degrees and minutes (as opposed to degrees in decimal form), they indicate the Ogden-Hinckley Airport in Ogden, Utah (north of Salt Lake City). If Steve's plane had crashed there, it would have been found much more quickly than the episode implies.
It seems very unlikely that a former astronaut involved in a serious test flight accident would be so unknown.The notoriety and recognition of astronauts diminished greatly after walking on the moon, but even at the time this series existed astronauts would have been known by someone in that community.