In one scene where they are on the side of the road, a speed limit sign is shown nearby. The speed is posted as 80. Since the movie takes place in July 1976 and Canadian roads weren't switched to metric until September 1977, this would mean the road was posted at 80 mph! In the unusual happenstance that this was a test road or the province was ahead of the rest of the country somehow, there would have been included the text "km/h" below the number - something all speed limit signs had at the changeover, to remind drivers it wasn't mph. Such text can still be found on speed limit signs near the USA border.