Pop singer Alecia Moore (P!nk) replaces Brittany Murphy as Gloria. Coincidentally, Pink sang a cover version of 'Tell Me Something Good' for the first film which can be heard in the opening credits.
The roles for Bill and Will the Krill, voiced by Matt Damon and Brad Pitt, were initially offered to Stephen Colbert and Jon Stewart. They had to turn them down due to scheduling conflicts.
There are an estimated 500 trillion krill, making them the largest animal population on Earth.
According to a 2011 Hollywood Reporter story, Warner Bros. dropped Brittany Murphy as a voice actor on Happy Feet 2 during early stages of the production after stories about illegal drug use appeared on tabloid websites. This is seen during Lifetime television movie The Brittany Murphy Story (2014). Coincidentally, the television movie was released the same year Robin Williams passed away.