Continuity mistake: MacGyver appears to be a novice at mountain climbing, but in the very first episode he mountain climbed like a professional.
MacGyver (1985)
1 continuity mistake in season 3 - chronological order
Starring: Dana Elcar, Richard Dean Anderson
Continuity mistake: During the car chase through the desert, the rear view mirrors on both cars disappear and reappear repeatedly.
The Eraser - S2-E2
MacGyver: Dreams are important, otherwise sleep is just eight hours of nothing.
More questions & answers from MacGyver
Answer: Late one night, Geoffrey used a covert listening device to overhear David explaining his barricade device to Janet which is how he figured it out.
How do we know Geoffrey really did use a covert listening device? They didn't mention him using one.
There was a scene of him using it when David told Janet about his barricade.