That's a good question. If I'm honest I haven't seen UT in probably 15 years.

I think it was the cornfield chasing parts? I also recall just being super creeped out by E.T. himself. The way he made sounds, the way his fingers move, etc.

The biohazard stuff you're talking about scared me, but I think just the sounds E.T. was making, not the guys in suits specifically.