His roles are at times credited, but more often they are uncredited, consisting of peripheral characters who have limited dialogue or appear briefly in a wide range of occupations such as newspaper reporters, hotel clerks and bellhops, taxi drivers, salesmen, police officers, military personnel, waiters, and bartenders.

[citation needed] Dorr's identification of himself, however, as a producer might be attributed to youthful exaggeration or was an unrealized intention, for no subsequent references have been found that credit him or even mention him in that behind-the-scenes occupation during his career.

He performed, for example, assorted roles in the 1927 revue Rufus LeMaire's Affairs; and the following year he portrayed Captain DeJean in the operetta The New Moon, which premiered at the Imperial Theatre in Manhattan on September 19, 1928.

A very small sampling of those motion pictures include Riders of the Purple Sage, Union Depot, Central Airport, Helldorado, The Mighty Barnum, Murder in the Clouds, The Case of the Missing Man, Show Them No Mercy!, She Gets Her Man, Love Before Breakfast, Sinner Take All, Snowed Under, The Firefly, Expensive Husbands, Big City, Criminals of the Air, Dangerous Holiday, It's All Yours, Captains Courageous, Missing Witnesses, Pardon Our Nerve, The Cisco Kid and the Lady, Test Pilot, Penitentiary, The Main Event, The Crowd Roars, Coast Guard, Sued for Libel, Gone with the Wind, and Mr. Smith Goes to Washington.

His on-screen sales pitch in that role, in which he convinces the story's leading character Dan (Mickey Rooney) to buy a wristwatch, is typical of the concise, quick-study performances that defined Dorr's career and made him so popular in cost-conscious studio casting offices.

Yet, his characterizations on television, like in films, were highly diverse and can be seen in at least 84 episodes of Westerns, crime and detective series, courtroom and hospital dramas, adventure programs, and sitcoms of the period.

[citation needed] Examples of Dorr's television appearances can be viewed today in video copies of full episodes from classic series, as well as clips from related productions that are available online.

[12] Five years after that appearance on The Jack Benny Program and subsequent work on several other series, Dorr made his last television performance on the sitcom Green Acres in "I Didn't Raise My Pig to Be a Soldier".