Pity the poor typeface designer, always seeing anachronisms in movies and television. Imagine how painful it must be watching a World War II movie only to see a document printed in Snell Roundhand Bold, a font invented in 1972. Here’s typeface expert Mark Simonson’s analysis of the lettering on “Mad Men.” More about the life of font designers in the new book Just My Type by Simon Garfield. This is part of a complete episode.