“The F.B.I. was aware of the potential for disinformation in the Steele election reporting and, in part to address that issue, made some effort to assess that possibility,” the report said. “However, in view of information we found in F.B.I. files we reviewed, and that was available to the Crossfire Hurricane team during the relevant time period, we believe that more should have been done” to examine whether that had happened, Mr. Horowitz’s team added.

The report’s newly disclosed footnotes add context to what prompted some of the worries and rounds of internal discussion among law enforcement officials.

In June 2017, for example — the month of the final wiretap renewal — an American intelligence agency received a report that indicated that two people affiliated with a Russian intelligence service were “aware of Steele’s election investigation in early July 2016.”

The footnotes also said an F.B.I. analyst told the inspector general he was aware of those reports but “had no information as of June 2017 that Steele’s election reporting source network had been penetrated or compromised.”

In addition, the newly revealed footnotes show that the F.B.I. team received three reports in 2017 raising the possibility that one of the sources for the Steele dossier was potentially influenced by a “Russian disinformation campaign to denigrate U.S. foreign relations.”

One source, whose identity remained redacted, offered two of those warnings, including casting doubt on material in the Steele dossier about Michael D. Cohen, Mr. Trump’s former lawyer. The report did not say what was wrong, but the dossier claimed that Mr. Cohen had met with Russian intelligence officials in Prague, which appears to be false.

The F.B.I. was warned a third time in 2017, apparently by a different source, who said that someone with ties to both Mr. Trump and Russia had claimed that reporting in the dossier about Mr. Trump’s activities in Moscow during a 2013 trip was false and the product of Russian intelligence services infiltrating Mr. Steele’s source network. (The dossier contained lurid allegations about Mr. Trump and prostitutes during that trip.)