Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is an action-adventure romantic comedy with big stars and one of the most hilarious and original snake scenes on film. It's a scene designed to please those such as myself who both love and hate snake scenes in movies.
The movie is similar to Romancing the Stone (1984) in that both involve a lonely female romance novelist who gets caught up in a romantic adventure and treasure hunt in an exotic location - the same sort things that happen in their books - and both movies have a scene with snakes. Romancing the Stone was an attempt to cash in on the success of the archeological adventure genre popularized by Indiana Jones and the Raiders of the Lost Ark, and it's no surprise that this movie start out with a parody of the snake scene in that movie.
The very first thing we see after the opening title is Dr. Lovemore (Sandra Bullock) and her companion Dash (Channing Tatum) lying down together on a stone floor where from their heavy breathing and dialogue we assume they just had sex.
Dash: "You were incredible."
Dr. Lovemore: "My heart is still racing."
Dash: "I felt it too."
Dr. Lovemore: "All thanks to your brute strength, Dash, and your knowledge of ancient Aramaic mathematics."
Dash: "Please, this has nothing to do with my two doctorates and my master's in Gender Studies, and everything to do with you, Dr. Lovemore."
Dr. Lovemore: "The truth is, I never thought I would find the Lost City of D."
At this point we know it's an obvious parody of a badly-written romance novel, but it gets even better. The camera pulls back and we see that they are tied up and lying on the floor of a huge torch-lit ancient tomb that is covered with hundreds of snakes, hissing and writhing around just like the temple in the Indiana Jones movie. Above them we see two henchmen and their captor holding torches. He tells them they led him right to King Kalaman's tomb and his queen's legendary Crown of Fire, which is obviously the treasure they were seeking. Then he tells them hew will be very rich and they will be very dead. From snakebite, apparently, though the snakes are just hanging around moving slowly and not doing anything at all threatening.
Dash and Lovemore also notice that there's something not quite right about the snakes. They begin to wonder why there are so many snakes in the temple, where they they came from, who they belong to, who feeds them - the kind of questions I ask here. They would be excellent at this. They realize the snakes as living animals and not just inanimate evil antagonists. The unnamed captor has no answer for their questions, so Lovemore, who is in real life the romance novelist Loretta Sage, decides to delete the snakes from the scene. Then she deletes the villains from her story. Dash tells her she still needs to write a story, so she deletes him and we see her sitting alone at her laptop computer. What we were watching was a segment from a book that she is writing that she realized was too unbelievable to finish.
Even though I love the parody and the common-sense reaction of the characters, and as silly as it would be, I'd still like to see the complete scene. Imagine if the writers of Indiana Jones thought the same way. We would have been deprived of an iconic movie snake scene and a great source of parody for this movie. Romantic adventure stories are hardly believable in any other way so why worry about a few snakes?
As far as I can tell, most of the snakes in the scene are CGI. The animators did a good job with their appearance, their, movement and tongue flicking, which makes it hard to tell. There might be a few live snakes in the close-up of the hanchman's legs, also, but it's hard to tell. This is where the movie is much different from the Indiana Jones scene. For that movie they used a combination of real snakes and fake snakes but no CGI snakes.
There is a much shorter version of the snake scene in the official trailer which you can watch on YouTube. It uses different views of the snakes, deletes them in a different way, and uses different dialogue, but it still gives a good idea of what happens in the final version of the snake scene as well as the rest of the movie.