I would want some tool that could help me escape from a stuck subway train, eg if there was an underground accident or it just stopped due to a power cut or something. Something that could break the windows, probably.

You say water is always available. Is that still true on the train? I wouldn't count on it on the London Underground.

Otherwise what you have looks pretty good. Certainly do the whistle thing. I'd make at least one of the torches a head-torch. Money is often useful.