1. Everybody not a noble being an indentured dung farmer toiling under slave-like conditions for feudal overlords. While true in some place in parts of the middle ages, it is not true for the best documented parts and periods of the middle ages, being the 13th century onwards in northern and western Europe. Instead this was a period of independents farmer paying their feudal in a mix of money and produce, with produce being more common in those areas that would later adopt the indentured servitude of dependent farmers.

2. Everything being produced locally. Again in the later parts of the middle ages this is not just true. By the late 14th century, for example, the Netherlands were strongly dependent on Lithaunian, Polish and Ukranian grain. And in the same vein the fabric industry of Europe was almost exclusively centered in Florence, the British Isles and the Netherlands from quite early in the middle ages.

3. Everybody but the clergy being illiterate. As early as the 14th century German farmers would keep written records of their possessions and the movement of their assets. We find written records kept by the local peasants who made up low-level courts at least a century earlier in places as distant as Finland or northern Sweden. Likewise literature written by French and German nobles exists as early as the mid-11th century.

4. Old parents living with their children. With the northern European pattern of late marriages that emerged in the 12th and 13th centuries this is quite unlikely. When people married in their late twenties and had children at about the same age, most old parents would already be dead and those who survived would still work as part of the village community, though likely at reduced efficiency.

5. Social classes being entirely rigid without any possibility for changing your status other than becoming a monk. The rigid legal distinctions between citizens, nobles and commoners gradually developed over the course of the middle ages, but didn't become entirely rigid until the mid-16th century or well into the renaissance. Before that it was entirely common for a succesful farmer to manage to get a weapon and a banged up armor and enter the service of a higher noble as a knight. At the same time it was also common for lesser nobles to lose their status as a noble in order to reenter the world of feudal obligation when times became too tough to scrape by on their own financially. Likewise the cities provided a venue for people to advance their status if they managed to get an apprenticeship or sink even lower if they failed at it.

6. Witches were burnt in large numbers by the Roman Catholic Church and frightened villagers. While the witch hunts did exist in Europe, they didn't happen in the middle ages, they happened in the renaissance and were predominantly carried out by protestant princes with what passed for due jurisprudence in the day. They weren't lynchings, they weren't medieval and they weren't really very catholic at all.

7. The Roman Catholic Church was in general able to control Europe and the beliefs of the time closely. By and large the Roman Catholic Church had to espouse views that were in the interest of the princes in order to uphold the privileged position of the church. Examples of this include the way the king was exalted to hold his own position in the official, catholic theology of the time and the way knights and the warrior codes held as part of chivalry being taken as a formal part of church doctrine. Other examples include of the church being less rigidly in control than commonly believed include the cheapness people got off with adultery and homosexuality in the middle ages, despite the theological arguments of it being the two worst sins. Lithuania being left relatively unmolested and involved in the eastern European politics for the first half of the 14th century despite not yet having converted to Christianity.

8. Nothing ever freaking change. I don't so much refer to how it is a big mash-up of all medieval periods in Hollywood as it is the view that the middle ages were a static period without significant social change. Apart from the evolution of Christian theology and the constant creep to the east of European culture, there was the rebuilding of the European trade network that broke down in late Roman times and the evolution of such typically western concepts as citizenship and monogamous, lifelong marriages as the only acceptable lifestyle. And then comes the technological advances, which, even if we discount the dark ages, ran the span from developing the wheeled plow to creating clockwork and ocean going vessels. Really, the middle ages were a dynamic period as is to be expected for something lasting that long.