The script held in the Crawford Collection in the AFI Research Collection contains the following character notes (excluding regular characters):
'DONNY MORGAN: "Typical" country boy, at home in the bush, a good, strong swimmer because his father's property borders the river. He can drive a tractor and so knows the basic principles of driving generally and he's watched Hogan operate the Toyota radio often and can do it himself without hesitation. He's a good enough kid, breaks the rules as set by adults occasionally, but doesn't mean any real harm. About 12. Must swim.
'BILL MORGAN: Donny's father, a battler, a man who puts a lot of stock by kids being "respectful" to elders, especially parents. Underneath the stern exterior, he's a fair man and there is actually quite a good rapport between Bill and Donny, even though Bill does come down hard on him at times. Early 30's.
'MITCH STEWART: Donny's city cousin up in the country for a couple of weeks. A boy who's dreamt of "adventure" and sees the country as an ideal place to live out his dreams. He's a poor swimmer but he's long on guts. He's about Donny's age and the two boys have a lot in common and get along well. Must swim.'
