Visible crew/equipment: When the Nihilists are ordering food at the restaurant, you can see the reflection of the camera and cameraman in the window behind them. Watch as the scene pans around and you can see the camera and the cameraman move as well. Could the person behind the camera be Roger Deakins? (01:34:20)
Visible crew/equipment: As The Dude enters his apartment, having left Ralphs, a stage hand can be seen in a window of another apartment. The stage hand ducks quickly.
Visible crew/equipment: Towards the end, when the Dude starts getting angry after Walter accidentally scattered the ashes all over him, you can see a black wire under the Dude's shirt going into his pants, most surely a microphone.
Visible crew/equipment: Towards the end of the movie when Dude, Walter and Donny are sat at the bowling seating area, the shot slowly moves forwards to centre Dude and Walter while Walter is talking. Just before Jesus interrupts them you can see the boom microphone reflected on the bowling equipment between Dude and Walter. (01:40:29)
Answer: Themmen plays a background bowler in pretty much all of the bowling scenes. I don't know if this is necessarily worth a credit, but I guess his agent disagrees with me.