These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Sequelitis: The original is a hugely popular 50s nostaglia funfest. This movie has only a few characters returning from the original (Frenchy, Eugene, the principal and her assistant, and the coach. All brief roles.) and introduces Sandy's cousin Michael in some weak attempt to connect the two movies. The plot is basically a Gender Flip of the first movie's plot and the results are... well, let's just say most Grease fans like to pretend it doesn't exist.
What Could Have Been: Paramount was envisioning up to three more sequels and possibly a TV series. Would Grease 3 have worked with the mid-Sixties and British Invasion music as a backdrop? Would Grease 4 have dealt with hippies? Would there have been a Seventies version, sorta like Dazed and Confused with musical numbers? We'll never know.