Re:"Mistakes" probably just such (Score 1)

remember this was not designed for computer
assisted solving, nor is it a real-life
(secret service etc.) cryptography situation
but a challange for readers of a cryptography
column.

also compare the background article at
http://www.eapoe.org/works/essays/gm41sw03.htm
quoting Poe:
"It is unnecessary to trouble yourself with the cipher printed in our Dec. number -- it is insoluble for the
reason that it is merely type in pi or something near it. Being absent from the office for a short time, I did not see a
proof and the compositors have made a complete medley. It has not even a remote resemblance to the MS."
which I think sounds credible enough (poor
printers)