Character mistake: In the bathroom scene with the fat man tied up, Kevin answers his phone upside down.
Character mistake: Dino puts up his "Elemento" for whoever takes down Marshall. Monarch then says there are only three of those cars (a Lamborghini Sesto Elemento) ever made. This is not true. Lamborghini didn't make three, they made twenty.
Character mistake: When Jesperson imagines himself as a Mountie his uniform is completely wrong and is not even the right colour. As it was his ambition to join the force and he has photos of RCMP officers in his cab, it seems unlikely that he would imagine himself in a completely incorrect uniform.
Suggested correction: It's not a character mistake, for the reasons stated; it's a clear factual error from the filmmakers.
It's a character mistake since it's his imagination and, as you stated, it's not something the character would get wrong.