Pretty cool man. I think ours in the US could really use an update soon. They're pretty boring compared to the bright and colorful ones from other countries.
Notes don't have a heads or tails. They have an obverse and reverse, otherwise known as front and back. Coins have a heads and tails. There was no mistake at Note Printing Australia or the Reserve Bank of Australia regarding the jumping of the $20 and going straight to the $50 note. The decision to go straight to the $50 note was because of the sheer number of counterfeit $50 notes in circulation. I'd like to know where you got the idea that there was some sort of mix-up because that simply is not the case. The mint DOES NOT have anything to do with banknotes. The mint DOES NOT produce banknotes. The mint DOES NOT issue banknotes. Note Printing Australia produces Australia's banknotes. NPA is NOT a mint and has nothing to do with the Royal Australian Mint. Polymer notes are tear resistant, not tear proof. The side with the signature is the front of our banknotes.