bottles that reached the field were full of water.
That's how Jocelyn got knocked unconscious from one. And that's how the bottles were able to travel 40 yards. You can't throw an empty water bottle that far. But a full bottle thrown from up in the stands can travel 40 yards. It's why so many stadiums now require the lids to be removed at sale (or if it's a can of beer then the can needs to be opened at purchase).