Anomalous Variations

Imagine that you have to revise the manuscript of a novel. A character's name has to be changed throughout the text. But you miss one appearance of the name. Thus, the novel is published with a minor inconsistency. Is this kind of what Guion is getting at with his:

"'...anomalous variations in reality.'" ?

-Poul Anderson, The Shield Of Time (New York, 1991), PART FIVE, "Riddle Me This," pp. 257-265 AT p. 261.

He says that the Asinaria was first performed in 213 BC and that Stefan Nemanya abdicated in 1196 AD although scholars recorded slightly different dates for these events. Why shouldn't scholars get the dates slightly wrong? 

I can imagine -

Reality I: Asinaria first performed in 212 BC and recorded as performed then;

Reality II: Asinaria first performed in 213 BC and recorded as performed then -

- but does Guion mean that the part of the timeline containing the event changes whereas the part of the timeline containing the recording of the event remains unchanged, thus generating an "anomalous variation"?