Although James Cagney found White Heat to be a good picture on a number of levels, in his 1985 autobiography Cagney called the film "another cheapjack job" because of its limited shooting schedule and the studio's decision to "put everybody in it they could get for six bits." Cagney was particularly irritated by the fact that he pressed them to cast his old friend Frank McHugh in the small role of Tommy in order to bring a touch of humor and lightness to the otherwise heavy piece. According to the star, Warners repeatedly agreed to do it, putting Cagney off until the first day of shooting when he was told McHugh wasn't available. Cagney found out later McHugh had never even been asked.

Cagney took credit for having the idea for the scene in which Cody sits in his mother's lap. He said he told director Raoul Walsh, "Let's see if we can get away with this," and Walsh agreed. But in his 1974 autobiography Each Man in His Time (which film writer Leonard Maltin has called "highly entertaining fiction with an occasional nod at the truth"), Walsh took credit for the idea and said the scene worked because Cagney and Margaret Wycherly made it so convincing.

The spectacular ending aside, the most famous scene in the picture is undoubtedly the one in which Jarrett gets the news in prison of his mother's death. The news is passed down from inmate to inmate at the prison mess hall tables until it finally reaches Jarrett, who explodes into psychotic grief, staggering around the room landing punches on everyone who gets in his way while letting out a kind of strangled, primal cry. Cagney was once asked by a reporter if he had to "psych" himself up for the scene. Cagney responded, "You don't psych yourself up for these things, you do them," reiterating his very non-Method philosophy that working on inward emotional motivation is a waste of time leading to a performance solely for the actor himself. According to Cagney, an actor shouldn't psych himself up to be the character, he should simply understand the character and play it for the audience. His only preparation for the scene, he later said, was remembering a visit as a youngster to see a friend's uncle who was in a psychiatric hospital. "My God, what an education," he said. "The shrieks, the screams of those people under restraint. I remembered those cries, saw that they fitted, and I called on my memory to do as required."

When Cody gets the news of his mother's death, Cagney plays his first reaction merely looking down, building into the emotional explosion. Years later, he explained to Los Angeles Times film critic Charles Champlin, "That first agony is private. If I'd looked up right away and started bellowing, it would have been stock company, 1912."

Walsh said of his star: "Jimmy, I can honestly say, was the best actor I ever directed."

Edmond O'Brien was also rather in awe of his co-star. In the book Cagney, author Michael Freedland said O'Brien found out how generous an actor and gentle a person Cagney could be. In a close-up the two were playing together, O'Brien felt Cagney standing with increasing pressure on the top of O'Brien's right foot, forcing the younger actor to move in that direction. O'Brien realized if he had not done so, he would have been out of frame and Cagney would have had the scene to himself. Freedland also relates how when the cameras were rolling, Cagney would look like "an angry tiger," but as soon as the director yelled cut, the star would quietly go up to O'Brien with a poem he had written and ask him in a whisper, "Would you mind telling me what you think of this?" When it came time to return to work, Cagney would plead, "Please, don't tell anyone about it."

Location work was done in the California towns of Van Nuys and Chatsworth (in a railroad tunnel). The explosive finale was shot in Torrance, Calif.

By Rob Nixon