Visible crew/equipment: When Cody and Zack walk into London's suite and find Moseby there, crewmembers are reflected on the glass door behind Cody. First in the wideshot, when Moseby explains the plan to capture the bird and then in Cody's close-up.
Nurse Zack - S2-E29
Visible crew/equipment: After Patrick dumps the cake on Moseby, he wipes some away from his eyes. At the start of the next shot, when a crewmember's finger moves across the bottom of the screen it cues Patrick, who makes eye contact with the finger, to exclaim his line, "You did this on purpose!"
The Suite Life Goes Hollywood (1) - S2-E36
Continuity mistake: After eavesdropping on Bud and Lou, when the 'hitmen' open the door, the things on the tray Bud is holding keep moving around between shots.
The Suite Life Goes Hollywood (2) - S2-E37
Revealing mistake: When Maddie and London are pulled off the cart by the horse, you can tell they use dummies. Look at the way their bodies move.
The Suite Life Goes Hollywood (2) - S2-E37
Revealing mistake: In the scene where London and Maddie fight and fall off the the saloon balcony, you can see that they are stunt doubles.
The Suite Life Goes Hollywood (2) - S2-E37
Revealing mistake: In the scene where Maddie and London come out of the saloon scratching and clawing, you can see that they're played by stunt doubles; the stunt double playing Maddie doesn't have any bangs, whereas Maddie has bangs.
Continuity mistake: When the boys are moving the laptop around on the table towards the beginning of the episode, one of the salt/pepper shakers gets knocked over onto its side. In the next shot, both shakers are standing up. It then alternates between one shaker standing and both standing for the rest of the scene.
Answer: Keep in mind, Muriel wasn't very popular. So the writers/directors must have thought it'd be a good idea to let go of the character. No one seems to be complaining.