Historical fiction that gets it wrong!

When I tuck into a historical fiction novel, one written in the time period I enjoy (1690-1815) nothing bugs me more than an author who just didn't put that little extra bit of research into making sure he/she has gotten the terms right.

For example, I'm reading Phantom Ships, an English translation of a French-Canadian novel set in the Seven Years War in Atlantic Canada. Every time the dialogue mentions "rifles" I want to through the book out the window. French Canadians, and the majority of British and Colonial American soldiers used MUSKETS up until about 1840.
Now, it may be that the translator got it wrong, but then again, the author may have used the French word for rifle and the translator just copied it into the English version.

It's like when I read Bernard Cromwell's "Redcoat" novel. It went along great until he mentions the British army marching into Philadelphia wearing "Shakos"!
British soldiers according to the 1768 clothing pattern wore Tricorns if Battalion/Hat companies or Bearskin Grenadier caps if Grenadier companies. Then you had the Light Infantry companies who wore a short cap while Highland Regiments wore bonnets.

It's the little details that really can through off a readers image of a good book.