Anvilicious: Lisa is extremely emphatic that religion and science cannot coexist.
Belief Makes You Stupid: All Springfieldians assume that it must be a skeleton of an angel, even though angels are said to be a religious concept without any scientific proof to argue for their existence and also said to be immortal and have no physical bodies. They just blindly go along with the idea. And after the angel is proven to be just a marketing ploy they are not angry for being so foolish, they just want to go off and buy the stuff the angel was marketing. However the stupidity of Springfield's people, religious or not, is a running gag throughout the show (Principal Skinnner and Superintendent Chalmers often complain about Springfield Elementary's low test scores in comparison to other schools in the state or the United States and note how the town is run by the incompetent and corrupt Major Quimby and the police are led by the lazy and incompetent Chief Wiggum).
Ear Worm: "Here's the angel! / See the angel! / It's my angel, no one else's! / Next to the rakes!"
Fridge Logic: The businessmen's Batman Gambit depended on Lisa (or someone else from her archeological dig) finding the skeleton in the first place. As such, you'd think they would make it a little easier for them. Everyone else but Lisa was about to quit by the time it was found. Unless they were afraid someone would find it too easily.