In Karl's first appearance, he is involved in a shoot out with Flynn against Wyatt Logan while they were arming John Wilkes Booth and his conspirators, George Atzerodt and Lewis Powell, with modern handguns.
1962: "Atomic City"
Karl is seen helping Flynn steal a plutonium core from an atom bomb.
1944: "Party At Castle Varlar"
Karl is seen scrambling with the rest of Flynn's men to grab what they can as troops approach their base of operations while Anthony Bruhl prepares a battery made of the plutonium core stolen from 1962.
1972: "The Watergate Tape"
Lucy and Rufus tell both Rittenhouse and Flynn about the location of the Doc, a defected Rittenhouse member. They both arrive at a location and a shoot out commences between the two parties. Karl strangles a Rittenhouse agent to death with a garrote wire in the conflict. Lucy and Rufus did this to create a distraction to save Wyatt. Flynn tells Karl of the trick they've fallen into when he realizes this.
1893: "The World's Columbian Exposition"
At the World's Columbian Exposition, Wyatt noticed Karl, recognizing him as one of Flynn's men. Karl reported back to Flynn, telling him that Rufus and Wyatt thought Flynn wanted to harm Theodore Roosevelt as expected. Later, Karl was tasked with holding Lucy hostage as Flynn and Harry Houdini broke into a building to plant a bomb to kill Thomas Edison, Henry Ford, and J. P. Morgan. Houdini escaped and knocked Karl unconscious with a pipe.
1927: "The Lost Generation"
Karl, along with Flynn and Emma Whitmore, shoot down Charles Lindbergh's airplane but keep him alive. Later, Karl shoots Dave Baumgardner to death due to his failure to bring modern weapons back on the mission. Karl later gets the opportunity to shoot Rufus to death in a catacomb, but is subdued by the team's temporary soldier, Ernest Hemingway, with a punch he deemed the "Hemingway Hook."
1954: "The Red Scare"
Karl does not accompany Flynn on any time adventures because he and another one of Flynn's men quit earlier.