Interesting point re embassies. In the past I recall that a foreign fugitive in a country was able to escape justice by getting to his country's embassy (or an embassy from a friendly country to their own), upon which the local police had no jurisdiction and could not arrest him/her. Isn't that how Julian Assange evaded any form of local arrest / extradition?
You can read about the Vienna Convention on Diplomatic Relations, but in a nutshell, the premises of a foreign mission are inviolable and not to be entered by the host country without the permission of the head of mission. That does not change the fact that the Canadian embassy in Mexico City is on Mexican soil. When you enter the embassy you are not in Canada, nor are you in quasi-Canada, you are in Mexico. Julian Assange was holed up in the embassy because the Ecuadorian ambassador wouldn't let the Metropolitan Police into the building.