Whenever I am walking on the paths or through the lines at Disneyland, I pick up litter. It's not exactly hard to find, and for gosh sakes it irks me to see the place trashed like that. Disneyland is like a second home to me and I like to treat it as such. People who come to visit DL are called "guests" for a reason. They are there to have a good time, but they should also have some respect and leave the place at closing time as perfect as it was at opening time.
The other members of my family have asked on a number of occasions what the heck I'm doing it for, when I reach for water bottles lodged in rocks in the Indy queue or plastic wrappers thrown in barrels around BTMRR. My reply- trash destroys the illusion. Besides, you only have to walk about five paces before you reach a trash can. You'd think with literally thousands of them and seeing them all day long, people would figure it out.
I know there is a small army of cleaning crew that scrubs the park 'till it shines and sparkles every night, but they are cleaning up after a daily party hosted for tens of thousands. Please, if you see litter at the park within reach, throw it away. Keep the park being the Cleanest Place on Earth.