I get the impression that Gamow was just trying to making the
narrative understandable by omitting certain effects. In what I've
read so far there has been no mention of Doppler shifts, although
I'd think they would have been quite obvious -- some of the motion
is ultrarelativistic, so I think the effects would have been quite hard
to describe. Also, there is no mention of the finite speed of vision.
For example, it would have been very dangerous to cross the
railroad tracks, since the train would have arrived just behind
its light.