October 28th, there seems to be something happening between Peterborough and Doncaster, only a limited number of trains are running between Kings Cross and Doncaster (and beyond) and they are diverted via Lincoln. With fewer seats available there won't be many at Advance prices, and they will take much longer than usual. If you found a cheap fare to Newcastle make sure it comes with a schedule from Kings Cross and not Euston.
The £66.35 ticket wasn't a fault in the system, it was a really odd rule. It's a one way fare that can only be bought with another one to make a return (round trip) journey! So to see it you have to select the option to ask for a Return journey. Which would be the logical thing to do if making such a journey.
As for Google Maps and driving times, the main reason for discrepancies was discussed a few weeks ago . If you are in the USA during the evening and ask for a route without a time parameter it will default to "Now" - but that will be the early hours of the morning in UK when the roads are quiet. You need to set the departure or arrival time, at which point it will use historical traffic data to give a better estimate. https://community.ricksteves.com/travel-forum/transportation/journey-planning-in-a-different-time-zone