Not sure how a note would be added to Ada Online, but I think this one should be fairly uncontroversial.
On Van's first day back at Ardis in 1888, the details of his arrival morph, starting with:
"My horse caught a hoof in a hole in the rotting planks of Ladore Bridge and had to be shot. I have walked eight miles." (P.189)
Then a few lines later, the narrator reports that "[h]is train had broken down in the fields between Ladoga and Ladore, he had walked twenty miles[...]"
Compare Van's changing story with the one Demon tells Van about Dan (on Demon's arrival at Ardis, also 1888):
"I met him in town recently, near Mad Avenue, saw him walking toward me quite normally, but then as he caught sight of me, a block away, the clockwork began slowing down and he stopped—oh, helplessly!—before he reached me."(P. 243)
Then a few pages later, dining with Van, Ada and Marina, the story becomes:
"The other day I chanced to walk through Pat Lane on the Fourth Avenue side, and there he was coming, at quite a spin, in his horrid town car, that primordial petrol two-seater he’s got, with the tiller. Well, he saw me, from quite a distance, and waved, and the whole contraption began to shake down, and finally stopped half a block away, and there he sat trying to budge it with little jerks of his haunches, you know, like a child who can’t get his tricycle unstuck, and as I walked up to him I had the definite impression that it was his mechanism that had stalled, not the Hardpan’s." (P. 255-256)
We're given the breakdown of a horse, a train, a town car, and Dan's own body.