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.
Alternative Character Interpretation: An only moderately altered interpretation of Nora has the side effect of altering the entire play. In the conventional reading, Nora is a naive innocent who gets a harsh lesson in the world and grows up to move out. A wholly different interpretation is that we're actually seeing a plot involving several conspirators, organized by Nora, to break her tyrannical husband's hold. The Doctor being "ill" is a setup—he's fine and the card with the X through it is a signal he's ready for Nora to take off with him as they've obviously had a thing going on. Nils Krogstad's reasons for going along with the setup are obvious (knowing he's on the chopping block at work because of Torvald, he has nothing to lose and everything to gain revenge-wise) and Nora is also, more kindly, masterminding the reunion of Krogstad with his old girlfriend and her old friend, Christine, who's been the victim of a similar domestic tyranny. Nora is in fact a Diabolical Mastermind/Magnificent Bitch orchestrating her husband's downfall.
A less elaborate example: Nora is often portrayed as a naïve victim of a domineering Torvald, but she can also be interpreted as the Hypercompetent Sidekick of a Man Child who is totally oblivious to how much work his wife puts into maintaining the façade of security and respectability that lets him see himself as a self-made success.
The "scheming Nora" idea actually begot a kind of professional Dark Fic in the form of August Strindberg's The Father, sometimes said to have been written in response to Ibsen's play. In that one, the wife and other really do destroy the noble husband with their selfish desires.
Misaimed Fandom: No, this is not a play about how evil men are and how terrible marriage is. It's more a play about how relationships fail when they're based on acting out social expectations instead of on mutual understanding and respect. Torvald and Nora never really know each other, because their entire marriage consists of them "playing house," acting out roles based on their assumptions about how the ideal Husband and Wife are meant to act. Meanwhile, Kristine and Nils are able to achieve a happy ending because they truly know each other, warts and all, and form a partnership according to terms that suit them as individuals.
Some Anvils Need to Be Dropped: After the truth comes out about how Torvald doesn't really love Nora for Nora, she removes her proverbial mask and tells Torvald why she must leave him. After spending the entire play masquerading as an airheaded ditz whenever her husband's around, she suddenly shows him how serious and well spoken she truly is. If the effect is jarring, the message is downright radical considering the time when the play came out.
Why Would Anyone Take Him Back?: Zig-Zagged. Torvald berates Nora viciously, then just as abruptly decides to forgive her because she is like a child and knows no better. She allows him to hug her and tell her how much he loves her, leaves to get changed - and walks back in with a suitcase to announce that she's leaving him.