[WillPS]

Can we clarify what is meant by CGI here - are we talking about the balloon being a computer generated render or real footage composited with a different background?

The latter. It's all real balloon, most the idents beside the original set were composites of real balloon and location (but not real footage of the balloon in that location).

The final set weren't real locations but were still real balloon - with the possible exception of the bungee jumper one?