Indeed. I've worked out a vague timeline that seems to raise certain inconsistencies...
For example, previous media interviews/articles have stated their walk began "one Thursday afternoon in August 2013."
However, in the book when they reach Porthallow near end of their first leg, it states that it's day 48. Counting the subsequent nights written in the book, it works out to be around day 58 by the time they call it quits at Pencarrow. The book states its early autumn and that October is approaching. They seek money from their children for train tickets to Polly's.
The first Thursday in August 2013 was the 6th, making this the earliest point of starting. The book also states "early August". But 58 days later is the 3rd October. This might sound not much discrepancy, from the book saying it was approaching October. But it still suggests an inconsistency.
However, I have found compelling evidence that they actually finished this leg no later than the 17th September, creating a 2 and a half week discrepancy.
What's also unusual is that when they walked through Newquay, they got soup at a homeless shelter and bought 25p pasties. What amazes me about this is that they didn't mention or meet their son who it turns out lived there at the time.
This of course doesn't mean they didn't do the walk, it just questions the account of it.