At the party at the Great Northern for the Icelandic investors, Ben Horne calls his brother over and orders him to remove Leland Palmer when he begins dancing. When the camera cuts back to Leland, after the Horne brothers talk, Ben can be seen calling his brother over again and having the same conversation again.
When James and Donna are talking to Madeleine at the dinner, her glasses change from her right to her left hand as she is getting up from the table.
We see the front of Leo's truck pulling into frame and we can see a shadow of the drivers side door opening and closing. But the door opens and closes so quickly it appears impossible for anyone to exit the truck that fast. And especially Eric Da Re's large frame could not have gotten out of the truck in real time.
When James is telling Donna about his Mother, the trees in the background display autumn colors, however Laura was murdered in Februray meaning the actual season would be late winter.