5. Knocking out enemies.

There are a lot of moments when, in an attempt to keep the hero 'kid friendly', writers will have them defeat their opponents with a good 2x4 to the head. The problem is that studies have shown that being forcibly knocked out can cause damage to the brain, leading to a series of mental and developmental issues. Your character can't walk away from getting conked on the head without a couple of after-effects.

4. Invincible, open archers.

In a huge battle, one of the best ways to take down your enemies before they got to you was to shoot them down while they were still a ways off. And the best way to make sure your archers could do this effectively was to make sure they didn't get shot back. Put up a shield wall, stick them behind a lot of people, or get them behind a real wall. Maybe all three.

(Side note for snipers: Stay hidden! If they can see you, they can kill you!)

3. Horses.

Horses were very expensive, so not everyone had them. Most farm animals had to be mult-functional, so cows or oxen were preffered for plowing, as they could be eaten as well, and sheep provided not only meat and wool, but their skin could be made into parchment ($$$). Usually only the wealthy or noble could afford horses, let alone horseshoes.

2. Filtered water.

Unless you get it directly from a spring, water is almost always contaminated in one way or another. In the medieval ages, the only safe way to drink water was to boil it and maybe run it trough a sack (assuming you could find a clean sack). Alchoholic beverages were more popular, as alchohol cleaned out the beverage anyway.

1. Female armor.

There's a ton of artwork of female warriors/huntresses online, and almost every single one of them is inaccurate and illogical. Think about it: The main function of armor is to protect the body. The main function of low collars, backs and high-cut dresses is to show off the body (shamelessly). The two do not combine well. A metal bikini is not going to stop arrows from penetrating your vital organs.

What say you?