Not experienced with the snowglobes, but I can speculate that the yellow tint is caused by water reacting with the plastic decorations inside or with the globe itself (if it's not glass). Also could be some lifeforms multiplying there, since while isolation maybe enough to hold water, the microorganisms had some way to sneak in.
I know the anser to the riddle, but I feel like it would be cheating in my case, since I'm a huge fan of that show
I have two riddles, both are also about snowglobes in films.
First one involves this rather unorthodox globe, I wonder if you know where it's from?
The second one is about a snowglobe which actually contained a whole world inside, but nobody knew that until the very last moment. This riddle is also about one TV show.
..But what about plasma globes? I have one, though it's pretty small and works as a usb gadget... These things were popular in the 80s and were often used as special effects props in various sci-fi movies.
There's also Elaborate Bytes' VirtualCloneDrive, been using it for a long time. It's fully freeware and very simple to use (supports BIN, not sure about CUE), but I don't know if it's available for OS other than windows.