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.
Crosses the Line Twice: In the second episode, an old lady insults the aged detective who comes by to ask about her son, due to their history together. Then she calls Rizzoli a "greaseball dyke cop". Then she uses a sardonic tone when addressing the black Frost as one of those "Affirmative-Action cops. Which island did you come from? Do you speak English?" This all happens in the space of about two minutes. Oh, and she's clearly Irish.
Genius Bonus: Whenever the Boston skyline is depicted, the weather beacon on top of the Old Hancock Building will match whatever weather might be shown in the following scenes. (It'll blink or shine steadily in either red or blue; the color patterns and their meanings are well known to Boston residents.)
Just Here for Godzilla: Some fans of Rizzoli & Isles may be attracted to the show because they are fans of Angie Harmon and Sasha Alexander from their old shows. Based on the ratings, it may now be a case of Come for the X, Stay for the Y (in this case, come for Harmon and Alexander, stay for the quality of the show).