You can place a rally banner inside the Prison
Making it useless, as units will ignore that unreachable banner.
Game Version:
      
          Steam Public
      
    Platform:
      
          Windows
      
    Making it useless, as units will ignore that unreachable banner.
 
 
 
 
Hmmmm, while it's certainly a very minor UX issue I don't think that there's a major problem with it. Players can just move their rally flag, it'd be a fair bit of work to change rally on arena and prison.