[ConjunctionJunction]

I'm not good at symbols, but I think the red balloon is supposed to represent Rick's emotions/anger. When we first see the balloon tied to the boat, Rick has his anger under control. Later on, Sam lets go of the balloon and Rick lets go of his anger. Here are some other theories:

'The Walking Dead' spoilers: The symbolic red balloon and what it could mean

5 Things You Might Have Missed in The Walking Dead "Try"

[Vermont Lt]

As long as it doesn’t go chasing some fat Japanese kid, I don’t care what the balloon stands for. I hated that movie as a kid.