Early on in part 2, Didi and Stu are standing in the kitchen, getting ready for a business dinner for Stu. Didi is on the phone with the babysitter. Stu is getting dressed. He is standing there in his shirt and tie, and in blue underwear. It pans away to Didi, then back to him. This time, his underwear is the same color/pattern as his tie. It pans away again, then back to him. His underwear are back to the blue color again.
The bag of flour says "floor"