If your child is old enough, before you head to the park you might want to review with your child what the 'rules' are so they are fresh in her mind. I don't know how old your child is but I see no reason you cannot have a timeout in a public space ... a few minutes in a 'quieter' area so she can collect herself. Be firm but loving in your parental role but remember ...big parks like Disney are very stimulating and tiring for little ones. Watch for signs of fatigue that can result in a meltdown and allow time for rest. Same goes for you.

Most of all, have a nice time.