Revealing mistake: When Ellen and the rest are on the ski lift, it becomes apparent that they are being filmed in front of a green screen because as the lift chair in front of them sways back and forth it disappears into it on the left side. (00:02:05)
Continuity mistake: Throughout the scene in the bookstore Ellen is shown alternately holding her mug by the handle or the cup part, as well as alternating hands.
Answer: This groundbreaking episode was in the fourth season, episodes 22 and 23.
Jason Feng