The episode title hints of the reveal of the Numeros agent Diez, which is "ten" in Spanish.
"Diez" may also be a play on "died" because Rizwan says that the Djin he knew is dead.
"Diez" may be referring to Rizwan because he joined the Numeros even though he later betrayed them, and that he is later being controlled by the microbugs that are injected into his body at the end of MISSION: ATLAS.
The title could have been purposely given as an inverted episode of Season 1 Episode 12 "MISSION: UNO" because the Numeros are ranked from 1 to 10. The title could be referring to a reversal story of a story arc.
"MISSION: UNO" may refer to the beginning of Uno's story arc.
"MISSION: DIEZ" may refer to the end of Uno's story arc.
The end credits are white on turquoise instead of blue, and the music used is a sad and harmonical tone. This is not to be confused with "MISSION: UNO", when the end credits are red and the music used is a villains' tone.