The bilingual shoulder badge of the border guard says "Duanes", instead of "Douanes".
Actual badges of Canadian customs officers show the terms "Services frontaliers - Border services" since 2003, not "Customs - Douanes"
The flag in the border office is not the right size - a Canadian flag is twice as long as it is wide.
Lapointe mentions that he requires his "Double double, with eight sugars." A "double double" is a common way of ordering coffee in Tim Hortons (a very popular coffee chain in Canada) and refers to wanting your coffee with two creams and two sugars. The addition of "eight sugars" therefor makes no sense.
When visiting Howard in Lachute, Guy Lapointe introduces himself as an "inspector for the Sûreté du Québec ". SQ inspectors wear standard issue brownish policeman clothes with a badge in plain sight, they do not wear civilian clothes much less berets.