The big no-no is asking a Canadian what part of America they come from.
Canadians may take offence if labelled American. Some Canadians get so annoyed about being mistaken for US citizens they identify themselves by wearing a maple leaf as pin badge or as a symbol on their clothing.
Actually it gets better:
Remember Arabs are not used to being told what to do
Visitors from the United Arab Emirates can take great offence if you appear bossy. They appreciate being looked after by staff who have been trained to understand Arab culture. For example, it is culturally insensitive to ask an Emirati whether they want bacon with their eggs or to include a half bottle of wine with the table d'hote menu.
When meeting Mexicans it is best not to discuss poverty, illegal aliens, earthquakes or their 1845-6 war with America
First I want to know how this cleared the "political correct" metre - seriously "Arabs are not used to being told what to do." Did this get in there by accident or is it a warning?
Finally I have to confess I think 2012 Olympics are doomed - and I say this with reference to North Americans flocking to London en masse expecting North American levels of service. Unless officials plan on importing people from the British countryside to work in London's hospitality industry, visitors are going to be extremely disappointed. But hey...nobody asked me.