A quick look suggests there are lots of missing lines in Africa e.g. in Namibia, Zambia, Zimbabwe, Botswana, South Africa, Kenya and Eritrea. However that is not to decry a good effort by the compiler. I have never come across a decent rail atlas of Africa, not even of South Africa. Does one exist? The continent seems to be devoid of railway enthusiasts.
I picked up a copy of 'World Atlas of Railways' by O.S Nock from a charity shop last year. A snip at £4.00. Very large and heavy but a decent map section. Published in 1978 but things in deepest, darkest Africa don't change much.
Also available 'World Rail Atlas and Historical Summary. Volume 7: North, East and Central Africa' by Neil Robinson, published in 2009. Barnsley, UK: World Rail Atlas Ltd. ISBN 978 954 92184 3 5. I haven't seen a copy so cannot comment on its content.
The thing I particularly like about this online map is the ability to track a route across a country at a glance. The underlying open-street map is good but it is the layer / rendering which makes the lines show up nicely.
The problem with Google is that you have to zoom in quite close to pick up the rail lines, at which point you lose the context and you have to scroll / pan hundreds of times to follow a whole route. Plus the lines are often in the wrong place! Plus the place names on Google seem entirely random. An example being Stoke-on-Trent which doesn't appear until you zoom in yet the six towns which make up Stoke-on-Trent are visible.
As for enthusiasts, try
http://www.friendsoftherail.com/forum/ A South Africa based website with lots a photographs. The phrase 'registration required' is generally incorrect and they are visible to all users. Must dash for another fix, I'm getting all excited again by those English Electric diesels with their bonnets and headlights.