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.
Adaptation Displacement: For baby boomers, the 60s television adaptation pretty much completely displaced the original radio series and movie serials in their consciousness. Later generations are familiar with the property primarily through the NOW Comics and Dynamite Entertainment comics series, and have little (if any) familiarity with either the radio series/movie serials or the TV series.
Ensemble Darkhorse: Thrown all across the board with Kato throughout the franchise. He began as a simple sidekick but over the years, he grew into popularity. Most modern versions have Kato as the muscle while Green Hornet was the central figure. In the movie, everything is taken to the next level. Kato was basically responsible for everything that the team did, from the gadgets to being the muscle. While Britt is still the main character and the one calling the shots. The movie does involve them clashing with each other over who was in charge. Most people agreed that Kato was the best part of the movie, so it's likely they intended the movie to be like this.
Shipping: Britt Reid and Casey Case. Hinted at in the radio series (in at least one episode Sentinel reporter Ed Lowery banters with Miss Case about her harboring a crush on Reid). Subtly made part of the subtext in the television adaptation in at least two episodes ("The Frog is a Deadly Weapon" and "Invasion from Outer Space"), in spite of firm insistence by creator George W. Trendle that the relationship between Case and Reid be kept strictly professional. Made "canon" in NOW Comics's "Hornetverse", where Britt Reid II marries Casey Case after his retirement (Trendle having died in 1972, the subsequent rightsholders apparently discarded any objections to a Reid-Case romantic relationship).
Broken Base: As Michel Gondry himself admitted in an interview, most fans of the property didn't care for this new comedic take on the characters. A small but dedicated group did like it, and actively defend it, however.
Hilarious in Hindsight: In a twisted form of Product Placement, Crystal Clear (played by James Franco) names the designer labels his henchmen are wearing; one episode of MTV's Spider-Man series, based off the movies James Franco is involved in, starts with Peter Parker referring to a shady guy and his henchman as "Dolce and Gabbana".
A lot of Jay Chou's Concept Videos could possibly act as Kato's entire backstory.
It's been known for some time that Seth Rogen and James Franco are good friends - with the release of this movie and now the "Bound 2" parody, you can safely say the Green Hornet and the Green Goblin have been going at it.
Ho Yay: Good God. Some people bring their Slash Goggles to movies. Some movies forcibly glue them to the viewers' faces.
Overly Long Gag: Whether intentionally or not, it's pretty funny just how long Crystal Clear goes on about why Chudnofsky isn't scary, as it becomes more andmore obvious that Chudnofsky will get the upper hand when he's done talking.
Awesome Music: Ladies and gentlemen, Al Hirt. The piece is not only enormous fun to listen to, but is so fast-paced that the King of Trumpet himself allegedly passed out when the recording was done.
Draco in Leather Pants: Double Subverted in the second broadcast episode of the TV series ("Give 'Em Enough Rope"), a female lawyer friend of Britt Reid's is captured by the Villain of the Week, and is rescued by the Hornet, in the next scene she's telling the story to Britt and gushing about the Hornet, wonders if he's really as bad as everyone thinks, and says she hopes he never gets caught, and if he does, she'll defend him for free. Subverted in that the Green Hornet really is a misunderstood, amligned hero. Double Subverted since she doesn't know that.