Yes, you are right - there is a mistake in the "Queen of the Colonies" passenger list. It lists William and Ann with children William, Charles and Ann. This should read George and Ann with children William, Charles and Ann.
The "Young Australia" agents list (no passenger list available) show William Horton and Family 2 1/2 passengers.
They only had one child when they migrated. Edwin Royston, Elizabeth's brother is believed to have travelled with them.Unfortunately we forgot to check this detail while at the Queensland State Archives.