‘Iron Man 3′ Cheat Sheet: What to Know Before You Go

By this time, you may have heard: "Iron Man 3" opens nationwide this weekend. But what you may not have heard is that there are important details about the film that you should probably know before you go.

We're not going to spoil anything for you here, we promise, we're just prepping you for what to expect, so that the spectacle which unfolds before your 3D-Glasses-covered eyes doesn't blow you away beyond comprehension. Which could happen, if you don't do your pre-viewing homework.

Who's Back

What would Iron Man/Tony Stark be without Robert Downey Jr.? Fortunately, we don't have to answer that question just yet, as RDJ suits up once again to play the flawed superhero and genius inventor. Gwyneth Paltrow more than pant-suits up in number 3, as she reprises her role as Pepper Potts, Stark Industries CEO and Tony's now live-in girlfriend. Don Cheadle also returns as Iron Patriot/Lt. Col. James "Rhodey" Rhodes -- unlike the transition between 1 and 2, when Cheadle less-than-seamlessly replaced Terrence Howard in the Rhodey role. And though he isn't returning as the film's director, Jon Favreau does reprise his role of Happy Hogan, Tony's chauffeur, assistant, and friend.

[Related: Get Local Tickets and Showtimes for 'Iron Man 3']

Important Newbies

Perhaps the most important newcomer to the Marvel universe is writer/director Shane Black, helming his first film since "Kiss Kiss Bang Bang" (2005), a quick-witted crime comedy that also starred RDJ. With Black's direction and writing (he also wrote the "Lethal Weapon" franchise), this feels like the funniest "Iron Man" yet, and with RDJ delivering plenty of past zingers, that's saying something.

Other newbies are Oscar winner Sir Ben Kingsley, who while playing the international terrorist known as The Mandarin, manages to steal scenes from RDJ. Also having a ball in a savory bad guy role is Guy Pearce, who plays shape-shifting mad scientist Dr. Aldrich Killian. Rounding out the important newcomers is Rebecca Hall, who plays Maya Hansen, a brilliant scientist from Tony's past who helps to complicate his future.

Our Story So Far

"Iron Man 3" is technically a sequel to both "Iron Man 2" (2010) and "Marvel's The Avengers" (2012). All the mayhem at the end of those two films has left Stark with a debilitating case of Post Traumatic Stress Disorder. And really, Iron Man's origin story in "Iron Man" (2008) adds nice character depth as well. So all three films are important homework. But if you don't have the requisite six hours to kill, thanks to National Post, here's all three stories jammed together in three short minutes, complete with super-cute superhero doodles.

Extremis Huh?

Since "Iron Man 3" isn't just mindless fluff, there is a bit of science homework to catch up on as well. If you're paying close attention, there are a couple of early scenes with both Hansen and Killian that introduce Extremis, a virus that when used correctly can help crippled people regenerate their limbs. But what kind of a bad guy would use that technology correctly? Even if you're paying close attention, connecting the Extremis dots may prove difficult, so before heading to the theater, we recommend giving yourself a quick Wikipedia update about Warren Ellis's 6-part "Extremis" comic book arc. While the film doesn't follow that arc exactly, the further explanation of the science could further enhance your viewing pleasure.

Where Do I Know That Guy From?

There's a few character actors in "Iron Man 3" that might make you slap your knee and wonder how you recognize them. James Badge Dale (Savin), portrayed Chase Edmunds in "24" (2004), PFC Robert Leckie in "The Pacific" (2010), and soon you'll be seeing him as Armie Hammer's big brother in "The Lone Ranger" (2013). You've definitely seen William Sadler (President Ellis) in at least one of his 137 IMDB credits, including "Shawshank Redemption" (1994), "The Green Mile" (1999) or "Die Hard 2" (1990).

And you can also play this game with Stephanie Szostak (Brandt), who you might recognize as Julie from "Dinner for Schmucks" (2010). Keep your eyes on her though, cause she'll also be appearing opposite Ryan Reynolds and Jeff Bridges in this summer's R.I.P.D.

Blink and You'll Miss

"Iron Man" creator Stan Lee has had a cameo in most the Marvel movies, and this one is no exception. But stay alert, because even though it's one of his better cameos, it's a quickie. Here's a hint: it involves beautiful women.

[Related: ‘Iron Man 3′ Flies High in First Reviews]

Best Time to Get Popcorn

No offense to Ty Simpkins -- who does an admirable job playing Harley Keener, a little kid who helps Tony Stark out in a time of need -- but there's plenty of Keener time, and some of it just might be a bit too cute for our taste. Feel free to refresh at these times.

Worst Time to Get Popcorn

There is a giant twist in this movie. It's about half way through. It's amazing. If you're dying to go get popcorn or seek some other relief, we recommend waiting till you've seen what you couldn't have seen coming.

Post-credits Alert

It's not a spoiler to say that this movie is like other Marvel movies in that it contains a post-credit scene. So you'll definitely want to stick around for that, no matter how badly you need popcorn. It's highly entertaining, but it also brings together the whole film in the same way a nice rug brings together the Big Lebowski's room.

So now that you've done your homework, go enjoy the show. And don't worry, we promise not to grade you.

See highlights from our exclusive "Iron Man 3" premiere red carpet livestream...