Cane Toads: An Unnatural History (1988)

Cane Toads is a documentary detailing the spread of Hawaiian sugar-cane toads (toads which live in the cane fields) through Queensland and then into the rest of Australia following a mis-informed attempt to introduce them to counter pests. Turns out they wouldn't eat the 'cane grubs' but they would multiply like no one's business... and they have no natural enemies in Australia at all, partly due to their poisonous skin.