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.
Considering the film was made only six months after the US Supreme Court struck down laws against interracial marriage, it's also Some Anvils Need to Be Dropped.
Hilarious in Hindsight: John mentions that Joey believes that all their children, presumably even their daughters, will be president one day. Forty-four years later, there's a part-African president, and many believe that a woman will absolutely be elected soon after his terms are over.
Harsher in Hindsight: During Tracy's monologue at the end, he mentions that the love he feels for his wife "will be there if I live to be 110!" He died weeks after the movie was finished.
Tear Jerker: Tracy's closing monologue of the film, the actor's last performance.
Katharine Hepburn never watched this movie because she couldn't stand to see Tracy's last work.
Unfortunate Implications: Christina brutally (and awesomely) fires her assistant (who is white) for loudly voicing a negative opinion of the marriage, but only scolds the maid (who is black) for doing much the same thing.
Values Dissonance: Perhaps it's a measure of the progress made when you have this contrast in the audience reaction with a large portion of the population in 1967: "She's marrying a Negro; that's crazy!" to now: "She's marrying a man she only met 10 days earlier; that's crazy!"
The wide age and life experience gap between John and Joanna can also play a larger part in modern audience reaction.