Clone Cadets - S3-E1
Continuity mistake: During the first training test, when Fives and Cutup have an exchange where the former tells the latter to flank right and gets a bad pun in response, Cutup is wearing Echo's practice armour (with a number 3 on it) instead of his own, which is marked with a 4. (00:10:38)
Answer: I guess that 1) the King assumed that Ventress' droids were meant to capture the Jedi, not kill him outright. When she yells at OOM-224 to shoot Yoda, she evidently failed that expectation. 2) Sending out a bunch of Droidekas after it is plain that Master Yoda has clearly won is not a sign of good sportsmanship, either.