Hi OP, hopefully someone can address the question of the laugh used, but for general feedback on the film, check out these

• /u/nmitchell076 in [How do historians think about the portrayal of Mozart in Amadeus?] (https://www.reddit.com/r/AskHistorians/comments/61equg/how_do_historians_think_about_the_portrayal_of) - includes links to three more posts

• /u/Aristocratie in [Amadeus portrays Mozart as recognized among his peers as a true genius, but always broke, a controversial figure, and not particularly embraced by the public at large in his time. Was this an accurate representation, and if so, what led to his universal recognition?] (https://www.reddit.com/r/AskHistorians/comments/92tx1r/amadeus_portrays_mozart_as_recognized_among_his)