Olivia Holt returned as a guest star for this episode (and several others in Season 4) after having left the main cast to pursue other projects.
Returns as a guest star, appearing as Jack's "evil" partner in the vision. Ian Reed Kesler Guest stars as the leader of the Black Dragon dojo. Falafel Phil Dan Ahdoot Guest stars as the owner of the local eatery. Notable Trivia
This episode marks a significant milestone as Jerry finally earns his black belt.
The episode features the main series regulars and several recurring guest stars who return for the alternate-reality sequences. Role in Episode Leo Howard
realizes the positive impact Jack has had on all their lives and, upon "waking up," finally earns his black belt. Cast and Key Characters
You can watch this episode and the rest of the series on the Kickin' It page on Disney+. You Don't Know Jack (2015) - (S4E17) - Cast & Crew - TMDB
"[S4E17] You Don't Know Jack " is the 17th episode of the fourth and final season of the Disney XD series , which originally aired on March 11, 2015. This episode is notable for being a Jerry-centric story that explores an alternate reality of the Seaford gang. Episode Summary
The disciplined sensei who suspends Jerry; "evil" version in the vision. Mateo Arias