All 50c coins minted that year were supposed to display a First Fleet ship and the dates 1788-1988 to acknowledge the bicentenary. But an unknown number of those were wrongly minted.
Check your change now: The 50c coin that could be worth $15,000 after Royal Australian Mint error
1988 Proof Set - First Fleet Bicentenary – M.R.Roberts - Wynyard Coin Centre
Rare 50c coin from 1988 minted to celebrate bicentenary worth $15,000
Rare 50c coin is worth up to 30,000 times its face value - have you got one in your pocket?
50 Cents - Elizabeth II (3rd Portrait - First Fleet Bicentenary) - Australia – Numista
Canadian Coins Worth Up To $88,000 Could Be Stuck Between Your Couch Cushions - MTL Blog
Australian Mint Coins: A Treasury of Numismatic Excellence
Rare Aussie coin could fetch $15k
Rare 50c coin from 1988 minted to celebrate bicentenary worth $15,000
Rare coins: An extremely rare 50c coin worth $15,000 is circulating in Australia
1988 Half Dollar - Canada
Rare 50c coin from 1988 minted to celebrate bicentenary worth $15,000
Detail on rare 50 cent coin makes it worth $800: TikTok