Continuity mistake: When we first see Odie on the double decker bus (about 22 minutes into the film), he is wearing a miniature souvenir "bobby" helmet. Then we see him chasing pigeons in the square hatless. Then the hat returns (did he have pockets to keep it in?). Then they are at a statue of Churchill - again he is hatless and we never see the hat again.
Factual error: The two uniformed police officers who take Dargis away at the end have haircuts that touch their collars. Plain clothed officers are allowed to be less stringent about their appearance, uniformed officers are most certainly not, and long hair like that simply doesn't happen.