Iùl not deep enough in photographer jargon to be sure I interpreted your mention of "low exposure" correctly, but as I'd see it, that photo is of low average exposure, and "normal" exposure on the light sources. And the fireworks do look superposed: that hints at long exposure, which "cameras" have been able to do before we even had camera lens.

I think that picture must be from 1937, as it seems to depict the german and soviet pavilion from the expo (as seen here on wikipedia: http://en.wikipedia.org/wiki/File:La_Tour_Eiffel_en_1937_con...)