Trump's apparent botching of the words drew particular attention in light of his repeated attacks on black National Football League players kneeling during the anthem.
And another added: "The man clearly does not know the words to the National Anthem".
The president had previously also courted controversy over his singing of the national anthem in May past year.
During one of his speeches, Trump even called a football player who refused to stand at attention during the performance of the U.S. national anthem "son of a bitch". He seemed more excited to sing along near the end of the song.
"You know who knows the words to the National Anthem?" Hmm. well, that's one way to show respect, I guess.
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In video footage, President Trump can be seen with his hand over his heart as the Star-Spangled Banner begins to play but he doesn't sing all of the words of the anthem.
It is also pertinent to mention Trump pushed the national anthem as a partisan issue shortly before the game during a speech to the American Farm Bureau Federation in Tennessee, tweeting, "We want our flag respected - and we want our NATIONAL ANTHEM respected also!"
And finally, most people tuned in to Monday night's game for, well the game of course, but others were excited for a separate reason: a new Black Panther trailer.
US President Donald Trump received a mixed reception from football fans in America's conservative south on Monday, a partial rebuke on his political home turf.
This is so intense right now as the Trump book, "Fire and Fury: Inside the Trump White House" written by Michael Wolff claimed that Trump was constantly forgetting things. "Colin Kaepernick", Charlotte Clymer tweeted, referring to the football player who kicked off the kneeling protests.