Pinky is obviously being lifted up from below as Mac supposedly pulls him up onto the catwalk, since he moves upward faster and more effortlessly than he could if he were struggling to pull himself up and being pulled up by Mac.
There is a visible bright yellow flash of an explosive charge when the truck's tires blow out as it runs over the spiked board, but a board with nails would merely puncture the tires with sharp metal points, without any chemical explosion.
When MacGyver is hanging from the bar hanging from the ceiling with Pinky holding on to MacGyver around the waist; MacGyver asks Pinky to get his knife and then his wallet out of his pocket. To do that Pinky was only holding on by one arm. Seems a teensy little bit unrealistic for such a feeble old man to hold on with one arm. Very much doubt that a fit man could.
While they are treading water in the tank, metal hand bars can be seen attached to the interior wall of the tank in addition to window ledges. He could have just held on instead of tiring himself out.
When Macgyver walks into the barn and turns off the smoke machine Karl and Neil are watching them on a TV monitor. Neil says "who is this stud? You said four flat tires was going to lose him" as if he didn't know Macgyver was there. Yet just a few minutes earlier both men watched Pinky and Macgyver walk onto the movie set from a second floor window.