Yes stuff falls off but it is picked up quick. In the Aladin parade the cammel with the giene taking a bath lost its head, the giene not the cammel. I have also seen a float get caught on a light pole in town square and break off some pieces. Like I said most never see this because it is piked up or coverd quick.
In one of the Christmas Fantasy Parades I saw Ariel's top(seashells) fall off. This event, that's happened more than once, is probably why she wears a body suit in the new parade everyday, instead of just when it's cold.
I've never seen anything fall off or even noticed it, but I'm sure it happens so I guess it's a testament to the people who take care of stuff like this. I have read some wicked things about WDW parades, though....
The King is back and he's ready to kick some tail. Do not mess with a mouse in black.
I personally fell off a float in the SpectroMagic parade (I was a Fantasia Ostritch) and Buzz Lightyear's foot went flying off the float in the DMGM Toy Story Parade. (The Ostritch jumped back on the Spectro float and Buzz's foot landed amongst the "worshipping" LGM's on the float. Luckily Buzz was high enough off the ground that if he didn't move his left leg it would''ve been hard for anyone to see my sock.)