National anthems are ticklish things, as anyone who has paid attention to the news of the past few weeks knows. What started last year as a gesture by one football player has mushroomed into a national debate about patriotism; about protest; about the patriotism of protest.

President Trump suggested a boycott of the N.F.L. and declared that players who knelt during the national anthem should be fired. Two weeks later, Vice President Mike Pence walked out of a football game in Indianapolis, apparently on Mr. Trump’s orders, after many players knelt.

Anger over perceived slights to the anthem is by no means a uniquely American phenomenon. China, for instance, recently made it illegal to play the national anthem on “inappropriate occasions,” including weddings and funerals. And anyone who violates “the dignity” of the anthem — such as with “distorted” or “mocking” versions — faces up to 15 days in police detention.

Most anthem-related controversies, though, are neither deliberate nor quite so dramatic. Sometimes, they are small things blown out of proportion. More often, they are just plain gaffes. Almost always, they happen at sporting events. Here’s a look at some of them, from the offensive to the funny to the simply absurd.