I do not use a save file downloaded from the internet.
I have 100% with all jumps, knife flights, under bridges, etc, completed.
Have not finished epsilon, submarine parts, and nuclear waste.
This is what I have found while trying to save a supercar in Trevor's hangar.
A hillibily which I cannot see apparently says ".. to rearrange your brain..." and sends electrical pulses towards Trevors brain. Due to this he has lost time and wakes up on the train tracks saying "not this again!!!" The game then prompts me to save. I'll see what I can find out more if I have time.
Happy UFO hunting!