Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is a Disney action/adventure/romance/time travel/fantasy movie based on a 1990s video game that cost $200 million dollars to make. I tend to avoid movies like this, but this one is actually kind of fun, and there's a lot of good parkour action in it. The third act goes overboard with all the cliff-hanging impossble action nonsense we always see in these big budget monstrosities, but the use of killer snakes in several scenes makes up for it.
In a nutshell, Dastan (Jake Gyllenhall) was an orphan boy who was adopted by the king of Persia and raised as a Prince. The king's evil brother Nizam (Ben Kingsley) needs to exploit the sacred city of Alamut to carry out his plans to take over the empire, so he persuades Dastan and his brothers to attack the city by convincing them that the Alamuts are hiding weapons of mass destruction. After they take over Alamut, no weapons of mass destruction are ever found in the city. (Why does this all sound so familiar?) In Alamut, Dastan finds a magic dagger that turns back time. Its guardian is a beautiful Princess named Tamina (Gemma Arterton). Tamina hates Dastan until she loves him, as movie heroines do these days. Their courtship involves a lot of yelling, abandonment, abduction, enslavement, and attempted murder before the romance, but finally Dastan decides to help Tamina bring the dagger back to where she can keep it safe. But it's not easy because a group of mercenaries called Hassansins are trying to steal the dagger from them. The Hassansins have the ability to travel in dust storms, they can attack out the sky, and shoot daggers from their sleeves. And best of all, their leader has the power to use venomous Vipers as weapons. You can tell that the this guy is super evil because his face is terribly disfigured. Most evil madmen are ugly and disfigured in movies. In real life they wear suits and ties and look exactly like Disney lawyers.
Snakes first appear when we see the Hassansin leader (who we'll call Hassansin) training his Persian Ninjas to fight and showing off his snake-handling skills to his boss Nizam. There is also some very cool snake-based decor in Hassansin's Ninja gym.
The first use of snakes as weapons occurs when Dastan and Tamina are being held hostage by a band of outlaws. Everyone is sleeping at night at an oasis when we see a viper tunneling through the sand and crawling out to attack a man. Dastan wakes up in time to grab the snake and throw it into the fire, but he's too late to save everyone after lots of snakes start flying out of the sand through the air fangs first into the necks of the bandits (Realism is so overrated.) So Dastan activates the magic dagger and goes back in time a few minutes to start everything all over. (I would give anything for an Undo Command like that.) The second time when the snakes start coming out of the ground Dastan is prepared, and he kills all of the snakes. The last flying snake dies when he throws the dagger and decapitates it in mid air. Its head falls in the outlaw leader's lap for a little comic relief.
In the next snake scene, Tamina and Dastan are at a temple trying to hide the dagger. Tamina is passed out next to the dagger so Hassansin sends a snake to crawl over her breasts, then down to swallow the dagger. The snake could have easily crawled around her, but movies still haven't figured out how to avoid needlessy sexualizing women while still making a profit from their adolescent male audience. Hassansin then retrieves the snake which crawls back into his sleeve. Later we watch him cut open the snake's belly and pull out the dagger.
Finally, there's a big fight scene between Hassansin and Dastan to save the world. (All Disney movies are contractually obligated to save the world. Those are the only stakes worth spending 200 million dollars on I guess.) Hassansin releases a Viper from his sleeve that is just about to bite Dastan in the face when - Princess ex machina - Tamina grabs the snake by the neck and smashes it into Hassansin's face fangs first. (You'd think he would be immune to his own snakes' venom.) Then Dastan stabs Hassansin and pushes him into an abyss, because movie bad guys always need a little extra killing or we end up with the bad-guy-thought-dead-comes-back-to-fight-one-more-time cliche. This is the rare movie where that does not happen.
We see two real snakes in the first snake scene, a Boa Constrictor, and a Python, but after that all of the snakes are CGI. Some of them are not badly done, and someone obviously studied snake tongues because we see a lot of realistic viper tongue movement, but everything else is the same old hissing, squishing, rattling, long-fanged, open-mouthed, flying through the air, mess of snake cliches that we see with most CGI movie monster snakes. No wonder people are terrified of snakes.