I don't think this is necessarily the case here, I think you just need glasses, but be aware that Google Maps takes into account live traffic information, so the route in google maps you plan may actually change when there are traffic delays when the page is reloaded and the route is recalculated. It's currently showing 19hrs 3 minutes and 1643km for me.
Not my route Nev but My comment was based on some strange distance info recently noticed by me over both short and local routes.
Ox has posted a route Im interested in, in the plan a ride section which had part of the trip as many hours directly over the trip he did in just a couple.
But I do need glasses as Im having trouble reading micrometers and fractional dial vernier.
Just add a few hundred Ks. was almost the best advice Ive ever had in this game.