I don't know what's more confusing: The fact that you searched for "Iran Coat of Arms" and turned up a Mexican flag; The fact that Google labelled it as the Singapore Coat of Arms; or the fact that you were searching for that to begin with. A wee bit of free time on your hands, Per?
As you likely know, it actually has to do with how Google does its image searches. The page upon which the Mexican flag appears probably has the phrase you searched for on it. Some people make a game of trying to find the oddest image results for phrases. I remember posting a topic about this here a few years ago; we had a few good laughs.