I got supplemental bonus for travel and 40% tax was withheld. My W2 doesn't show the supplemental income or taxes withheld. Do employer provide this in W2 or any form?

I received my supplemental bonus as air tickets for travel to my home country. My 40% taxes were withheld. Now I received my W2 which doesn't include my supplemental income or 40% taxes withheld. Do employer provide this information in W2 or any other form? Also wanted to know if the taxes are 40% for supplemental income?