Mac Gyver's use of the microphone cable as a defibrillator would not work. There is virtually no significant amount of voltage, and certainly not sufficient to defibrillate because these are simply connected to an audio input. The hum heard is simply 60 hz hum from the system's loudspeakers.
The East German troops at the beginning appear to be wearing the Nazi Germany uniforms from WWII.
When Mac is talking to the pathologist he says that the mystery substance was good for nylons and stopping the heart of a kind old man. The actor playing the old man is 43 and clearly not old. Perhaps this scene was filmed before the role for the man in question was cast.