[caractacus]

The map misses a road which heads out from Cambridge to Colchester that shouldn't be difficult to spot given that it's called the 'Roman Road'. Even the Romans should be able to spot that.

https://frrfd.org.uk/archaeology-and-history/roman-road/

[toyg]

It only includes roads and locations mentioned in two sources: the Peutinger map ("tabula Peutingeriana" [0]) and the Itinerarium Antonini [1]. Clearly you've found where those sources lacked precision.

[0] https://en.wikipedia.org/wiki/Tabula_Peutingeriana

[1] https://en.wikipedia.org/wiki/Antonine_Itinerary

[leoc]

The routefinding also seems to be seriously imperfect. This journey from London to Tripoli takes the land route around the whole of the Eastern Mediterranean coast: https://omnesviae.org/#!iter_OVPlace427_TPPlace292

[dafman]

It also seems to be missing part of Ermine Street from London up to Royston and then to Peterborough

[TimTheTinker]

I think it only lists the roads that were noted in this particular route scroll.