Among the contradictions, Trump flatly said the FBI director he hand-picked was "wrong" about Antifa and said he disagrees with top federal officials over timing for a coronavirus vaccine.
The FBI, Antifa and White supremacists
During the debate, Trump was asked whether he would disavow White supremacists and militia groups inciting violence at anti-police brutality demonstrations around the country.
In his response, the President pivoted to blaming left-wing agitators -- specifically, the far-let movement of so-called anti-fascists called Antifa.
"I'll tell you what. Somebody's got to do something about Antifa and the left because this is not a right-wing problem this is a left wing," Trump said.
Biden interjected, noting that Trump's "own FBI director said unlike white supremacists, Antifa is an idea, not an organization ... not a militia. That's what his FBI director said."
"Well then, you know what? He's wrong," Trump responded.
Wray later clarified last week in another congressional hearing that "Antifa is a real thing. It is not a fiction."
"(CDC Director) Dr. (Robert) Redfield said it would be summer before the vaccine would become generally available to the public. You said that he was confused and mistaken. Those were your two words. But Dr. (Moncef) Slaoui, the head of your Operation Warp Speed, has said exactly the same thing. Are they both wrong?" Wallace asked.
Trump said: "I disagree with both of them."
"I've spoken to the companies and we can have it a lot sooner. It's a very political thing because people like this would rather make it political than save lives," the President said.
Trump also claimed during the debate that White House coronavirus task force member Dr. Anthony Fauci, who has served as the nation's top infectious disease expert for decades, changed his mind about the impact of wearing masks to prevent he spread of the virus.
When Biden brought up Trump's inconsistent mask use and how federal administration officials said their use further prevents coronavirus' spread, Trump claimed, "And they've also said the opposite."
"Dr. Fauci. Dr. Fauci said the opposite," the President added.
Fauci has changed his stance on masks as the science on the issue evolved, but the need to wear one is not an ongoing debate, as Trump implied.
Fauci is among the federal officials who moved from discouraging mask use among non-medical workers to encouraging mask use for everyone.
Mail-in ballot security
The President also repeatedly attempted to sow doubt in the elections system during the debate, spreading disinformation about mail-in voting and repeating many of the false claims that he has been making all year -- including the lie that mail-in voting leads to massive fraud.
"They're sending millions of ballots all over the country," Trump said. He added, "This is going to be a fraud like you've never seen." He later said mail-in voting is "a disaster" and claimed that "it's a rigged election."