Sadly, I will be responsible for some of them.
One question I get asked a lot (no really, people love to talk to me about this) is "how will you prove you've done it? Does someone from the Guinness book of world records come to watch?"
Not really. The onus is on the challenger to obtain and submit proof that they have successfully made a world record attempt.
I aim to do this by making a series of short video clips (10 seconds or so) that contain me, the station name, and that day's newspaper*. If I then have these videos verified by a trusted 3rd party before the next day's tube service begins then I humbly submit your honour that I have indeed been to each and every station over the course of one calendar day.
Furthermore, by having an independent third party start and stop a watch at my first and last station, and transfering to him/her a card containing the said video clips, the time the challenge has been completed in is also verified.
A sample video is up on youtube...
*Following a conversation with Tony C, the newspaper idea might not be as solid as I thought due to editions being available the night before. So I might improve it by having some independent person sign the paper, or write a code number on it, in the morning before I start.
Tube Challenge Blog >