"The Curse of Shirley" features examples of the following tropes:
Bag of Holding: A double example occurs when Shirley asks the Bagges for handouts as an Old Beggar Test. Muriel obliges her by grabbing a carpetbag out of her apron pocket, and then pulling a coin pouch, a pie, and an entire tea set on a tray out of the bag.
Ironic Birthday: It's on Eustace's birthday that the curse has not only prolonged its stay, but generally made Eustace's life worse for it.
Sympathy for the Devil: Although Shirley has a right to let Eustace remain cursed, she does pity him, if only because Courage wants it removed on his behalf. As such, she grants Courage a chance to help Eustace undo his plight.
"Courage in the Big Stinkin' City" features examples of the following tropes:
Uncanny Valley: The Violin Girl. As if having a live-action little girl composited into a cartoon wasn't creepy enough, she then turns around to reveal a horrific claymation face.