Ness was the real agent leading the investigation against Capone. However, the film portrays him as more naive initially and far more involved in violent confrontations and the tax case than he was historically. His personality is dramatized.

Malone is a completely fictional character created for the film, serving as Ness's mentor and providing experienced muscle. He has no direct historical counterpart in Ness's real team.

Stone is a fictional character, added to the team for his marksmanship skills and to explore themes of ethnicity and loyalty.

Wallace is a fictional character representing the financial investigation angle. The crucial tax investigation was primarily conducted by IRS agents like Frank J. Wilson, not Ness's Prohibition unit members.

Capone was the real gangster target. De Niro's portrayal captures his public image, power, and capacity for violence (like the baseball bat incident, based on a real event but with different victims/context). Specific scenes are dramatized.

Nitti was a real, high-ranking member of Capone's organization. His portrayal as a primary enforcer is accurate, but his depicted actions (murders of Wallace/Malone) and dramatic death are fictional.

The film accurately depicts the backdrop of Prohibition in Chicago (c. 1930-31) and the historical conflict between federal agent Eliot Ness and gangster Al Capone.

Ness did face significant challenges due to pervasive corruption within the Chicago police force, judiciary, and city politics, which protected Capone's operations.

Ness did assemble a small, trusted team known for their incorruptibility (True). However, the iconic members depicted (Malone, Stone, Wallace) are fictional creations, not the real historical agents (False).

Ness's team did conduct numerous successful raids on Capone's illegal alcohol operations, significantly disrupting his business, as depicted.

The dramatic horseback raid and shootout at the Canadian border is entirely fictional, though liquor smuggling from Canada was common during Prohibition.

Capone's organization did use violence and intimidation, and Ness did face threats. However, the specific murders of Wallace and Malone as depicted are fictional.

These characters are fictional, and their dramatic murders orchestrated by Nitti did not happen.

This iconic, stylized sequence inspired by Eisenstein's Battleship Potemkin is completely fictional and did not occur.

While Ness's raids hurt Capone, the crucial legal breakthrough came from investigating Capone for income tax evasion.

Ness's Prohibition unit provided some support, but the primary investigation and case-building for tax evasion were done by IRS agents (Frank Wilson, Elmer Irey), whose roles are largely given to fictional Wallace.

Obtaining insider financial testimony was key to the tax case (True). The character Walter Payne and the specific circumstances of his cooperation/protection are fictional (False).

There were real concerns about jury tampering in Capone's trial, leading Judge Wilkerson to famously switch the jury pool at the last minute. Ness's direct confrontation with the judge is likely fictional.

Nitti died by suicide in 1943, years after Capone's conviction, and was not killed by Eliot Ness.

Al Capone was convicted on several counts of income tax evasion in 1931 and sentenced to prison.

The film is accurately set in Chicago during the height of Capone's power and the enforcement efforts of Prohibition.

The film utilizes real Chicago locations or convincing recreations, capturing the architectural style of the period, including famous spots associated with the era like Union Station.

Costumes accurately reflect the typical men's and women's fashion of the early 1930s in urban America.

Vehicles, firearms (especially the Thompson submachine gun), telephones, and other technology appear authentic to the period.

Effectively portrays the atmosphere of Prohibition-era Chicago: rampant organized crime, widespread political and police corruption, illegal speakeasies, and sudden bursts of gang violence.

Scenes depicting raids on illegal breweries and warehouses visually represent the activities of Prohibition enforcement agents like Ness's team.

The depiction of the courtroom during Capone's trial reflects the typical appearance and procedures of a federal court in that era.

While the specific location/action is fictional, the setting represents the smuggling routes used during Prohibition, though perhaps stylized.

The film's cinematography and production design successfully evoke the visual feel and mood of 1930s urban America, particularly its darker, crime-ridden aspects.