One of the Americans tells a character to 'shut your boombox.' Boomboxes did not exist in 1814.
Oak's costume is so comically unrealistic that she looks like some 1960s music festival escapee.
No one had steampunk goggles in 1812.
Some of the men have belt loops on their trousers. Belt loops were not invented until 1922.
They took the French trapper's canoe to travel faster, but once in the water they're coasting.