While Chandler is taking the message about Joey's audition, there is a drawing of a face on the MagnaDoodle behind him. He hangs up the phone and crosses to the door to begin writing the message. The MagnaDoodle is now completely blank, but Chandler did not erase it. Chadler's hand is seen going to the erasing button for a second, but the camera changes, and Chander is writing the message without any time in between to actually have erased it.
Looking back at Episode 19 (The One with Joey's Fridge (2000)), Rachel's hair is about 3 inches past her shoulders, maybe 2 inches above her sternum. Here in Episode 20, it's well past her breasts, only 3-4 inches above her waist. That's about 10 inches of growth in about a week's time. One can see the layer that separates her natural hair from the hair extensions, and she keeps the extensions for the rest of the season. She goes back to her natural hair length the next season in The One with Monica's Thunder (2000).
When Joey returns home towards the end of the show, the 2 Joey Special pizzas disappear from the kitchen counter.