firearms in medieval Europe?

The first machine gun was intented in 1718 by James Puckle in England. It was called the Defense Gun or the "Puckle Gun"
It was a single barrel flintlock gun with multiple revolving chambers, who was operated by a hand crank.
It was not a commercial success, only very few was sold, obviously because of how slow it fired the bullets (9 rounds a minute), but it does show that a machine gun was invented in Europe before the invention of the multi barrel Gatling gun.

I believe you can't put stuff in goofs if it was made on purpose.

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The occasional use of anachronisms was one of the things that made this film so much fun to watch.

Yeah it was just meant for fun. Like in Van Helsing

Clark: 'Jonathan Kent; isn't it a little past ur bedtime?'

Actually, I'd say late 19th, early 20th century. Sure, the style of dress is meant to invoke Medieval Europe, but the presence of cartridge arms seems to indicate the late 1800s. One of the characters is seen wielding an 1892 Winchester rifle. Either way, still a very fun movie.

Did they ever mention the year or location?

Heck, it could be the distant future!

When the witches took to their brooms I was disappointed that there wasn't some sort of medieval Apache Tomahawk attack helicopter. After all, Da Vinci did have sketches for ideas for a helicopter.

Everyone gets everything he wants.

They didn't care back then and just took the story as a different world with different rules. Only today do you see people upset when a world with freaking flying, magic wielding witches has guns in it because it doesn't fit the time period (which was never stated BTW).

Agreed, I didn't mind the enormous troll slamming two people aside wielding a tree and neither did the man exploding in a mess of guts and insects bother me.

But the fireamrs where a 'bit' over the top.