The scene where Mark Addy says "Yayyyy" because the audience gives no reaction to Chaucer was improvised by Addy because the extras didn't speak English (they were Eastern Europeans) and had no idea when to cheer.
Several of the named knights were, in fact, real, though many of them are from different time periods. Ulrich von Lichtenstein was a knight and author who was said to have invented the concept of chivalry and courtly love. Piers Courtenay was a descendant of Edward I, born in the 15th Century. Sir Thomas Colville, Edward III's disguise, was a knight from the 13th Century. Lord Roger Mortimer was the lover of King Edward II's wife - Isabella of France - and was hanged by the Black Prince.
Geoff Chaucer threatens to immortalize the summoner and the pardoner in literature, and the real Geoffrey Chaucer did just that in his Canterbury Tales. The Pardoner and Summoner were portrayed as two of the most corrupt and vile people imaginable in Medieval society. They are also homosexual lovers.