Tunguska

Krycek:  ...Son of a bitch, get back here! [Mulder walks back to the car, bends to look in window.] Mulder:  What did you say to me? Krycek:  What? Mulder:  You called me a bad name.

Mulder's lucky that that's all Krycek did at the time.  Considering the number of times Mulder decided to use Krycek as his personal punching bag he's lucky Krycek couldn't haul up and slug him back.

General Punkesque Behavior

Name calling:  Mulder's very childish response after realizing that Krycek did hand him that bust.

In typical Mulder fashion when he and Scully split up Mulder barks orders without ever uttering the word "please."

As usual, Mulder never lets a little thing like time of day keep him from calling on people.  This time it's Marita Covarrubias he wakes in the middle of the night.

Exactly on what authority did Mulder go to Russia?

Criminal Activity

Assault and Battery:  He didn't commit this crime once or even twice, he hit someone three times.  Once again (on all three occasions) Mulder uses Krycek as his personal punching bag.

Trespassing:  The fact that he had to dig under a barbed wire fence should probably have been a hint that his presence was not wanted.

Just Plain Dumb

What the hell is wrong with Mulder?  He couldn't find someone else to play interpreter?  He knows he can't trust Krycek why would he even consider putting himself in the position to be dependent on him?