A few interesting excerpts from:
http://sify.com/news/columns/fullstory.php?id=13624256
Mughal-e-Azam has long been the definitive reference for an opulent film, the epitome of the “myth as history†format of Indian traditional cinema of the early 20th century.
the enhancement of scale, using opulence as a virtue of visual narrative, and taking artistic liberties with a published work of literature are all strikingly similar to Asif’s own attitude in Mughal-e-Azam to a story filmed earlier: in 1960, Mughal-e-Azam was a successor to Filmistan’s Anarkali (1953), with both tracing their roots to Imtiaz Ali Taj’s famous play, Anarkali, which is still a text of study in postgraduate courses in Urdu literature.
Mughal-e-Azam is historically inaccurate on several counts, despite dealing with historical characters. Thumri, which is a 19th century musical form, is used along with Kathak and its costumes in a 16th century court. Even the Sheesh Mahal (Glass Palace), the royal bath of queen Noorjahan, has been presented as a huge dancing hall of the Mughal emperor, Akbar. While Anarkali could well have been one of the several nautch girls in the harem, Prince Salim fighting Akbar for her is not part of historical documentation.
The script of Mughal-e-Azam has been written, or rather rewritten, by four writers; emphases were changed from the earlier Anarkali and the scale enhanced to epic proportions, creating a cinematic masterpiece in which myth and history are indivisibly one.
The huge commercial success of the new-fangled dialogue EPs resulted in HMV releasing the entire audio track of Mughal-e-Azam in three LPs. Home video had not been invented,
The coloured Mughal-e-Azam is shorter in duration compared to the black-and-white original. The refurbished colour scheme broadly follows the palette of the Pyar Kiya To Darna Kya song, the only portion of the film originally shot in colour. The technique is amazing: it manages to create tones on a grey monochrome range, although the colour schemes fall short of a full classical depth and flair.
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(I have read it many times recently that PKTDK was the only MEA song picturized in color. This is contrary to what I saw in the 60s where the Sheeshmahal song (where Madhubala tricks Dilip Kumar to drink that makes him unconcious, near the end of the film) was in color too. It may very well be that PKTDK was the only MEA song shot in color and the other reels of MEA were artificially colored back then??)