I realize it's Mothering Day in the UK, but I'm in the USA. I just mentioned in a meeting at work that we planned a system go-live over that weekend and felt bad that we were making people work on Mother's Day (March 18).

I know very well the US' Mother's Day is in May, but things have been so hectic planning for this upgrade that I never gave it second thought when I looked at my prized VRCC calendar and saw 'Mother's Day' listed on March 18th.
As a continuous improvement idea, maybe future holidays noted on the calendars could have a country code designation in parens next to the holiday? e.g. Mothering Day (UK)