The episode is black and white, because the most important "race" on Earth is dogs now in this post-apocalyptic scenario. Dogs don't know colors, their sight is black and white. This, however, is a common misconception. Dogs can see color but the colors are muted.
*SPOILERS*
The "dog" is shown to have the ability to fire an on-board gun, which it has already used against the two male characters. When Bella is stuck up the tree it makes no attempt to take what appears to be an open shot at her with a clear line of sight, instead opting to sit & wait. This allows her to escape but makes no sense given the previously demonstrated effectiveness of its weapon.
This is not a plot hole. When the dog is stuck in the wrecked car, it breaks off the leg with the gun in order to escape. It's subsequently seen hobbling around on three legs.
The "dog" is shown to have the ability to fire an on-board gun, which it has already used against the two male characters. When Bella is stuck up the tree it makes no attempt to take what appears to be an open shot at her with a clear line of sight, instead opting to sit & wait. This allows her to escape but makes no sense given the previously demonstrated effectiveness of its weapon.
This is not a plot hole. When the dog is stuck in the wrecked car, it breaks off the leg with the gun in order to escape. It's subsequently seen hobbling around on three legs.
At 19:05 the character mocks the dog as being unable to climb the tree because of the dismemberment of its arm. If the robot is recognized as a dog ( as she did in a radio message earlier) then the limb in question should have been referred to as a leg.