Visible crew/equipment: When Sheriff Harry Truman takes the call from Pete Martell at the police station, a reflection of a seated crew member wearing headphones (it actually looks very much like David Lynch!) is visible in the glass divider of the office the Sheriff enters to answer the phone. Clear as day. (00:05:13)
Visible crew/equipment: When Sheriff Harry S. Truman first leaves the station, film crew are visible as they dolly back across the Ford Bronco. (00:05:55)
Visible crew/equipment: At the diner, when Bobby asks Shelly if she needs a ride home, the reflection of a boom microphone is visible in the horizontal glass mirror behind Bobby (far left of the screen). (00:16:15)
Visible crew/equipment: When Josie and Catherine are arguing at the mill, just as Pete says, "Oh Catherine, please," he moves toward the chair, and the reflection of a crew member wearing a cap is visible on the window, at the left side of the screen. (00:32:25)
Visible crew/equipment: When Bobby is released by the police, he speaks to his friend in the hallway of the station about the possible identity of Laura Palmer's killer. To avoid eavesdropping, Bobby tells his friend that they should speak outside. As they walk through the glass doors towards the exit, Bobby encounters his father and two other people. Tape markers are visible on the floor placed at their feet. (00:55:53)
Visible crew/equipment: While Truman and Cooper are at the bank, when they take the safety deposit box and walk over to the table, there's a green tape mark on the floor by Truman's feet. (01:03:20)
Visible crew/equipment: At the very end, Sarah is alone while she's lying down, but when she has the sudden vision of Laura's necklace being dug up, the reflection of a crew member is visible in the round mirror. (01:32:50)
Visible crew/equipment: Donna overhears her father and mother discussing Laura's golden heart necklace and the picnic video. Then, just as Donna enters the bedroom, there's a white T-mark on the floor at the bottom of the screen.
Answer: The answer to pretty much any question beginning with "Has David Lynch ever explained _______?" is: no.