Other mistake: When Cooper is on the floor after being shot, as he's signing the check, he is doing so with the pen closed, and proceeds to click it open as he hands it back to the room service.
Other mistake: When we are first introduced to Leland Palmer and Benjamin Horne, they are discussing a contract in front of a large, lit fireplace. A couch (on which Leland is seated) is in front of the fireplace. Strangely, the flames of the fire are visible through the couch, and also Horne's legs are at one point. (00:11:09)
Answer: The answer to pretty much any question beginning with "Has David Lynch ever explained _______?" is: no.