Transferring between companies can->usa and vacation issue

If i previously worked for the canadian office and transfered to the US office after getting a greencard, then was laid off from the US office, should i be entitled to my vacation time off, from the time spent at both offices? or just the one in the US?

You should check with your HR not here as this is an internal issue. In my experience, when I was transferred to the US, it means that you are leaving your Canadian position because they have to hire a replacement for you. This means that your vacation pay will either be paid out or transferred. In my case it was transferred.

Besides, vacation pay in Canada usually represents 4% of your salary (hours worked). If you've been working in the US (you didn't say how long), do you think you're entitled to Canadian vacation pay? I don't think so, unless the Canadian office and US office split your salary in half.

Usually the job offer states the conditions for the transfer.