1. Apartment changing numbers..
Apparently, the creators realized that Monica and Joey's apartment are not on the ground floor so they can't bear a single digit number..
2. The One With The Bullies
You could see the head of the man holding the dog.
3. The handwriting on the board. The One with the RaceCar Bed
Joey must have had an invisible sidekick.
4. The One where No One's Ready
The stain magically changes its size. Dried up?
5. The One with the Red Sweater
Santa's elfs at work again?
6. Oh my dear Manny. The One with the Male Nanny.
When the puppets change hands on their own.
7. The One With The Mugging
Not even Joey is that good with beers and juices..
8. The Magical Necklace.. The One Where Ross Finds Out..
PS- Credits for all the pictures goes to comedycentral.