Misused word: On route
Example of misuse: They were on route to Blaydon Races when the bus wheel flew off
Word it is confused with: En route
Corrected example: They were en route to Blaydon Races when the bus wheel flew off
Explanation: En route is a French phrase, which, according to dictionary.com, was adopted into English in the late 1700s. As the phrase is French, so is the spelling and in French en and on are separate words.