Goof: Monica's resolution is to take more pictures of the friends. In the scene where Joey and Phoebe argue about Joey learning the real names of the guitar chords, she seems to walk out of the setting, reappears, stands between Joey and Phoebe and a picture is taken from the direction of one of the crew members. She smiles and walks away without saying anything to the photographer. The missing three friends are not in this scene!
Note: It is possible that Monica set the timer on the camera.