Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is not one of the best Sherlock Holmes movies. Even though it stars Christopher Lee, who was a very good Holmes, his voice is dubbed because the movie was made in Germany, so we don't even get to hear him act. There's a snake scene, but it's not very good either.
Holmes and Watson's nemesis Professor Moriarty has been killing people with a cane that shoots long sharp blades. (It has a nice little snake carved onto it's ivory handle.) Moriarty stole a priceless necklace that once belonged to Cleopatra from one of his victims. Holmes gets the keys to Moriarty's office where he finds a case with a mummy and immediately knows the necklace is hidden in it. He removes the top then avoids getting killed by a lock rigged to shoot anyone who tries to unlock it. Then he searches for a secret compartment. When he finds and opens it, a snake comes out, apparently put there to attack anyone who tries to take the necklace. Holmes waits patiently until he can strike and grab the extremely slow-moving snake. He grabs it with two hands and then puts both hands inside the compartment and brings them out without the snake. I guess we're supposed to think he crushed it to death inside the compartment and left it there. That makes no sense, because he still has to find a box in the compartment, but it avoids the need to show and explain the fate of the snake. They didn't need to make a fake snake with fake blood, or even use a dead snake. Regardless, Holmes somehow finds the box containing the necklace underneath all the snake blood and guts in the compartment.
The snake used to guard the necklace is a harmless Boa Constrictor. But even if we want to believe that it's a dangerous venomous snake, how does it survive in the compartment? Snakes need warmth, food, water, and a place to dispose of their waste, just like all of us. Does someone open the compartment to clean it and feed the snake? Maybe snake duty is reserved for Moriarty's henchman interns.