It's obvious Dave isn't driving the "Night Of The Cow" sketch.
Watch the dog humping Kevin in the "First Time" sketch. He's eating cheese which they had to put next to Kevin to get him to stand there, and the "humping" motion is actually Mark pushing him from behind.
In the first Mr. heavyfoot sketch, you can see the wire tied to Dave's back, so that when he falls forward, they can yank him back quickly.
In the "Poo Guy" sketch, after Bruce shows the billboard of him holding a plate of poo, you can see hes cracking up a bit. But gets back into character.
Bruce: Scott? What are we supposed to do? I mean, first you were gay. Right?
Bruce: And then you were really gay.
Kevin: Oh, oh, then he was irritatingly gay.
Dave: Oh yeah.
Kevin: Do you remember that?
Scott: I don't recall that one, Kevin. No.
Bruce: And now you're UN-gay? I mean, what are we supposed to believe, Scott?
Scott: Well... you know... LISTEN LYNCH MOB! I don't care what you believe, okay? I'm having a hard enough time adjusting to being straight so back-off!
Look hard at Kevin's face in the "First Time" sketch. His left eye is swollen, and chose to wear glasses to cover it up.
The end of the "Scott's Not Gay" sketch was cut from syndication due to content, as well as parts of the "Victum" sketch for time. The "Poo Guy" sketch was almost cut, but the members fought hard to keep it in.
The products Mark has were real product ideas someone pitched to the group, but none of them liked outside of a joke. The only fake one is the blue bumper sticker that reads "We're behind you, Scott (get it, huh?)"