When the aliens are examining Steve, he is undressed. When they test his bionic eye, he is wearing his shirt for a split second, then he is naked again.
Steve breaks through the cave wall at an entirely different spot from where he saw the red glow.
The type and placement of the electronic equipment changes between shots of Bigfoot knocking it off the tables.
The revolving "ice tunnel" in the aliens' mountain base was a then new attraction at the Universal Studios Tour. However, the attraction had a tram running through the tunnel. When the producers of The Six Million Dollar Man filmed sequences there for this episode, the tram-rails used on the Universal Tour ride were conspicuously covered with cloth and a forced-perspective miniature was placed at the far end of the tunnel, which is especially visible as Bigfoot stands before it.
Same footage used for showing each of the first two floodlights burning out on the ground.
Steve passes the same part of the cave tunnel twice --- with the same blindingly-bright curved-sided floor-lamp --- during his jog toward the rotating ice-tunnel.
Obvious stunt double when Steve rolls down the dirt hill during his fight with the Sasquatch.
When the aliens bring Steve into their "operating room", several crew members are reflected in one of the legs of the gurney as it is wheeled across the frame.