When Lorelai and Rory say they add red and green M&Ms to their cereal, Chris says he's "down with that." In an earlier episode he gets on Lorelai about buying cereal with too much sugar.
Fully green, deciduous trees and green grass are clearly seen in several scenes. Only problem is- this episode takes place in late December. (Also, in one outdoor scene the cast & extras are wearing cold weather apparel but their breath isn't seen.)
Lorelai tells Rory that the family hasn't done anything related to Christmas while Rory was in London. This isn't possible since they have a 3 year old child living in the house. They would at least have to have presents from Santa on Christmas morning. Also, Christopher seems fine with holding the holiday for Rory to get back, but he probably would have been upset that Lorelai wasn't considering Gigi in her plans.