Firstly, the "floats" were lorries, and if you'll remember, the lorries open from the side with tarps, so they picked a theme and decorated their float accordingly.
Secondly, instead of passing out sweets, like you might do in the States, the floats are voted on, by the public, with donations. Each float has folks with buckets collecting coins. It's mostly the copper coins [one and two pence ... now I know what to do with them!], but that is how the public casts their vote for their favorites.
Oh wait, thirdly, they used Uncle Sam as the mascot to donate to your Carnival!
There is also a panel of judges [I wish I would have gotten their photo!], but I couldn't tell if that counted more or less than the money!!!