According to the official website and Amazon, every volume of the BD/DVD series for Kuroko no Basket (both limited and normal editions) will contain animated bloopers, which will be based on the extra section of the original manga series.
There is also an episode 22.5 listed on the 8th volume of the BD/DVD series. It is unconfirmed whether this will be an unaired special or a recap episode.
This manga deserves more than one season. We have shit manga out there with endless episodes but nice things only get OVA specials? Don't get me wrong I'm glad to hear about more Kurobasu but the original material is too good for just one season.