Yeah. The MIBIII Script has been leaked or released or something online and everybody and their mothers have read/reviewed it. I'm posting two of the best reviews, each giving away as many spoilers as possible, some of which I'll feature below, so stop reading if you want to remain clueless.
News In Film had the first review. The information they detailed is as follows:
"Following the formula of the second film, Men in Black 3 opens on an introduction to the central villain. He’s named Yaz in the script, but the character has reportedly been renamed to Boris and will be played by “Flight of the Conchords” star Jemeine Clement...
Yaz is described as an “evil hippie/biker badass right out of Easy Rider” with “a huge mane of hair” and “a big handlebar mustache that frames his grubby unshaven face.” These features are all “strangely alive” and we later learn Yaz is an assembler, meaning his independent body parts are capable of reattaching themselves after a fight...
After a night of his own celebration, Jay returns to MIB headquarters to find himself in an alternate reality where his partner is dead (!) and Agent Kay is instead played by… Clint Eastwood. That’s in the script, but probably a long shot considering the 80-year-old legend retired from acting in 2008...
Kay’s untimely death means a “sophisticated” Earth defense system was never built to stop missiles that are now hurtling towards the planet. In order to rescue humanity and revive his friend, Jay has to travel back to 1969 and stop Yaz from murdering Kay in the past...
Jay links up with Agent Kay of 1969 (played by [Josh] Brolin), who’s investigating dry ice and hitting people over the head to “neuralize” them. (There’s also a funny bit about a giant room-sized neuralizer, one of the many winks for fans.) Again, like Men in Black II, the second act is centered on convincing Kay to assist with pressing MIB matters and developing their “old” rhythm."
Bleeding Cool finishes this off with:
"At this point we learn that Agent Kay was killed in Florida in 1969. Jay uses an iPhone app to travel back in time and meddle with cause-and-effect again. If he doesn’t save Kay, then the whole world is going to burn in 2012.
In the past, which is where we spend most of the screenplay, there’s a lot of business about Agent Jay’s race. Not only do we see every possible joke about his being black that you can imagine, it even gets him accused of being an alien. Okay – not just being black but being black and driving a caddy that he’s only driving because somebody made an assumption about his race...
JoBlo say that the script features Yoko Ono, Jimi Hendrix, Castro, Kareem Abdul-Jabbar and Andy Warhol as cameo characters, and that every last one is revealed to be an alien. There’s a Spider-Man joke that will need a little tweak now that Andrew Garfield has the part too...
Ultimately, the world is saved by playing a videogame. Not a videogame from the present day, however, and not even a videogame from 1969 – this one was released in 1972. In the script, it is revealed to have been invented by oracular aliens who know the earth will one day need it to stave off a massive alien attack.
Boris wants to kill the game developer aliens and prevent the invention of the defense system. Again, many questions have been raised about how much this whole cause and effect loop here does or doesn’t make sense. Are these aliens seeing an actual future? A potential future? Apparently, it’s not clear. Some say it doesn’t need to be.
After the climax, there’s a Sound of Thunder-style joke at the end of the script which shows how current history hasn’t quite been reverted to normal. It’s a gag that gets right to the heart of the Men in Black concept, and it even means a Men in Black 4 would be impossible to make without actually changing things back again. I’ve made it sound rather more serious than it actually is."
