I was at Disney about 7 or 8 years ago and got in with an entire camelback full of vodka and cranberry. This was before I had kids so I was just drunk uncle along for the fun.
Guy at the gate opened it up and looked at the red tint, looked at me, looked back at it then shrugged his shoulders and handed it back and said have a great time. I think they've tightened their rules since then
Camelback would have been awesome, I don't think Disneyland even sells beer in the park unfortunately. I remember disneyworld did at just about all the cart vendors lol today's California adventure so we'll see what they have today