What makes this such an unlikely trilogy is that the first film was so self-contained and simple -- it wasn't bogged down with the kind of loaded mythology that can be unspooled over subsequent films. In fact, there was barely enough plot to keep that original movie together (the sequel was more or less just a rehash of the first with Bangkok filling in for Las Vegas and a monkey in place of a baby). Still, if it makes money, the studio has to make more. And here we go again on the "Hangover" train.
1. It Doesn't Follow the Formula of the Other Two The original "Hangover" featured three dimwits (Bradley Cooper, Zach Galifianakis, and Ed Helms) who lose consciousness during a bachelor party and awake to find their friend (Justin Bartha) missing and their memories of the night before completely gone. The sequel was pretty much the same, although Bartha wasn't missing he was just kind of... hanging out away from the rest of the guys. This movie takes a different approach, which you can tell from the opening scene of supporting character Chow (Ken Jeong) escaping from a maximum-security prison in Thailand. From there, things get really nuts. Bartha is taken out of the equation but in a more logical way, and there are no instances of mistaken drugging or amnesia or "oh my god what happened" nights. 2. It Doesn't Take Place in Las Vegas All of the advertising for "The Hangover, Part III" has centered around the fact that the Wolfpack is returning to Las Vegas, which is where the original film took place. While this is true for a portion of the movie, most of it actually takes place in Tijuana, which makes sense given its notorious reputation for debauchery and criminal exploits.
3. It's Not as Atrociously Sexist as the Other Two... Maybe it was the structure of the two other films (and their bachelor-party connection), but they tended to paint women as nagging, whiny hangers-on with very little to actually contribute to the story besides someone to mock or lie to. (The female character with the most dimension was Heather Graham in the first one... and she was a prostitute.) For this one, women aren't seen as the ultimate enemy but rather something worth fighting for. They represent the normal, calming relationship that exists outside of the hedonistic free-for-all that the movies used to lionize. Even Graham makes a return appearance, but as a woman with a full life (even if she is literally barefoot and pregnant in the kitchen. D'oh!).
4. ...Although if You're an Animal Lover, This Might Not Be the Movie for You "The Hangover Part III" starts with a giraffe decapitation (endlessly teased in the trailers) and continues to include chickens being shot, thrown out a window, and smothered with a pillow, and two dogs having their necks broken.
5. There Isn't All That Much "Crazy" Stuff in This One The earlier films made it a point to emphasize (with neon lettering and double-underlines) how outrageous they were. The locations were meant to drive this point home (Las Vegas! Bangkok! And now Tijuana! That's where anything can happen!) But even their attempts at outre humor seemed to fall a little flat, with the explanation of the night before always failing to live up to the visual gag of waking up surrounded by mayhem. Thankfully, "The Hangover Part III" doesn't attempt to indulge in the levels of vulgarity that the first two achieved. It's still very R-rated, but doesn't shove it in your face.
6. Zach (Once Again) Steals the Show Interestingly enough, they have decided to center the movie around Zach Galifianakis's character, Alan, who has gone off the rails following his father's death. In fact, the craziness of the movie starts when they're driving Alan to rehab. The character goes through a noticeable arc and it's great that director Todd Phillips and his creative team decided to at least try to emotionally anchor the movie (somewhat). It might not always work, but the scenes between Galifianakis and an un-credited Melissa McCarthy are easily the most enjoyable in the movie.
7. Oscar Nominee Bradley Cooper Is Pretty Wasted Bradley Cooper, coming off of last year's amazing "Silver Linings Playbook," is more or less a background extra in this movie (although one that gets to say the F-word a lot). Although, he does get one truly amazing moment: as he's dangling off the edge of Caesar's Palace and Alan is trying to take a cell phone photo of him, he first gets annoyed and then pauses and says, "Did you get it?" It's a very real, very funny little bit and a testament to Cooper's power as an actor.
8. Stay Through the Credits It's not exactly a Marvel movie teaser, but it's worth sitting through the credits (don't worry, you won't have to sit through the whole thing). It's like an alternate reality glimpse of what this movie could have been (you'll be very thankful it wasn't like this).
9. John Goodman Is Great After appearing in a bunch of Oscar-caliber movies last year ("Argo," "Flight," "ParaNorman"), Goodman gets to turn in an appropriately hammy performance as the chief bad guy. He gets one of the best lines (too good to spoil here) and gets to thunder around, menacing people, and barking orders. It's unlikely "The Hangover Part III" will follow in those films' Oscar-nominated footsteps, unless a new category is created for Least Believable Depiction of a Giraffe Decapitation.
10. It Really Does Feel Like the Last One Thankfully it goes out on a high note; this is easily the best of the three. Whew.