The arena is actually an abandoned mill which production designer Graham 'Grace' Walker stumbled upon in rural Georgia. With its existing rusted steel and broken windows, it already looked apocalyptic.
The "Sheriff Ammo-Bag" the Governor uses at 24:31 is the bag Rick left behind in episode 1.1, Days Gone Bye (2010), of The Walking Dead (2010).
One of the Woodbury survivors in this episode, Brendon Cornwell, is the uncle of the first set of twins (Adelaide Cornwell & Eliza Cornwell) to play Judith Grimes.
From this episode, until the end of the season, Judith Grimes are portrayed by a different set of twins. Loudyn Case & Leighton Case replace Adelaide Cornwell & Eliza Cornwell. The girls were between four and seven months during filming.