Who would arrest you? The United States? You broke no law of the USA. Canada? There's not even an exit control so you will meet no one who could fine or arrest you. Police in Canada while being in Canada? No such silliness happens.
Overstays in Canada are less usual than the USA because it's really hard to get work without a SIN and you can't get a SIN if you are not here legally. If you are just visiting, there's not really a problem -- except, of course, that you need to pay for all health care out of your pocket.
And while there are no exit checks, Canada still knows when you left, either the US border guard shares the info or the airline manifest does.