Goofs

Even though they are being continuously drenched by the hose while putting out the fire, as they run away from the well just before the explosion, they are noticeably drier. As MacGyver sits up after the explosion his clothes are only slightly damp and his hair is mostly dry and neatly styled. He should still be soaking wet.

The windscreen of the truck they transport the dynamite in is either very dirty or mostly clear in different shots during the trip. Mac's windshield wiper is also either up or down in different shots.

If the escaping well-gas could actually be touched off merely by the small spark from a somewhat-distant shattering light bulb that was swinging in a strong breeze, which incidentally would have been carrying the gas from the well away, also, and dissipating it enough that there might not be enough of a concentration to ignite, then surely the small debris-fire that was still burning very near the well after Mac detonated the nitro over the well would have re-ignited the gas that was still coming up.

The "linkage spring" McGyver fixed with the pen spring is actually a throttle return spring and its absence would not cause the engine to stall but rather the engine would not return to idle when the throttle was released and keep running at a high rpm.

The drill pipe on the rig is clearly labeled "PLASTIC". Actual drill pipe would be steel.

A highway or major road can be seen in the background of land that's supposed to be so isolated that Mac had to be flown in by helicopter.

The "nearer" line of metal pipes is too close to the "farther" line for the wheel-rims on the raised side of the derelict jeep to land onto the pipes.

Richard Dean Anderson screws up a line when MacGyver first greets his friend and says he has a fancy hat and ten gallon boots, which don't exist.

When MacGyver and Bill first enter the cabin to get the dynamite a gloved hand briefly enters the bottom right of the frame to steady to boxes in the foreground.