I was testing one of my space ship maps in HL1, when I noticed an interesting Physics error, hence the title.
I have a sort of pit, not too long.
When you walk straight at it, not pressing anything but w, you fall right in, but when I walk at it and press ctrl for duck, I skid over the surface.
Interesting huh? it seems when Gordon ducks, his feet disapear, and his body keeps going, but falls to the ground shortly after.
What an odd dude.