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.
Freud Was Right: It pains Fanny to see Mary Crawford riding the horse Edmund once established as solely for Fanny's use...
The necklace scene. Fanny has two possible chains for her cross—one from Henry and one from Edmund. Henry's doesn't fit in the designated hole. Edmund's fits just fine.
Hilarious in Hindsight: Mary Crawford blames Fanny for her brother eloping with Maria Rushworth, saying no harm would have been done if she had just married him, and his relationship with Maria "would have all ended in a regular standing flirtation, in yearly meetings at Sotherton and Everingham." A few decades later, it's like Anne Bronte read that alternate ending, wondered, "What If?", and wrote The Tenant of Wildfell Hall to answer the question.
Les Yay: Fanny/Mary Crawford — much more subtle than Emma/Harriet but definitely there.
Edmund: Well, Fanny, and how do you like Miss Crawford now?
Oh so much between Frances O'Connor and Embeth Davidtz in the 1999 movie, at least for as long as Fanny isn't a serious contender for anyone's hand in marriage.
Macekre: Some people feel that various adaptations of Mansfield Park itself, notably the 1999 movie and the 2007 film, are vile travesties of the book, based on statements by filmmakers in each case saying that they didn't find the character of Fanny very interesting. Other people feel that the adaptations are an improvement, on account of Fanny becoming less of an Extreme Doormat.
Misaimed Fandom: Sorry, Jane, but some readers still judge Fanny Price and Mary Crawford by their first impressions.
Ship-to-Ship Combat: Mockingly between Jane and Cassandra Austen, according to their niece Louisa Knight.
Also, Edmund is opposed to the play on many grounds - but one of them is the 'indecency' of his sisters being on stage in front of an audience, even a small family audience, something we would not bat an eye at today. Granted, the participants then pick a romantic play and use the rehearsals as an excuse to flirt all over the place, so his objection still ends up justified by modern standards, but his incredibly deep objections when Tom begins the scheme are still puzzling to modern readers.