I enjoyed the film. Responding to a comment about the carves wooden door, he dug through it, but hit metal, seems to me the door was very thick with metal plate inside.
I feel Defoe escaped through the manhole as he was nowhere to be seen at the end.
I think I would have eaten the fish before the dog food.
Seems he wasn't upstairs much, did he venture there.
The penthouse was his prison, about survival.