I collected the current coins, the current bills, a slightly older set of bills, a couple of older coins, a special $10 note, and a squashed penny from The Interislander ferry.
Below is a chart showing when changes were made to New Zealand’s bills and coins. (The change from a yellow line to a green one indicates the switch to decimal currency.) 
It seems like every government bank, bureau of printing and engraving, or monetary authority likes to taunt visitors with displays of cancelled bills no longer able to be used as money. Here’s the display at the Reserve Bank of New Zealand:
