Revealing mistake: During the exchange between Hevy and Cutup regarding Echo's enjoyment of their dull posting, the left pauldron of Hevy's armour is positioned weirdly, clipping through his arm at the bottom. (00:01:34)
Revealing mistake: When Grievous falls to the ground as the Gungans throw plasma balls at him, the lance General Tarpals stuck through his torso blatantly clips through the ground. (00:15:03)
Old Friends Not Forgotten - S7-E9
Revealing mistake: When Anakin says to Obi-Wan that if they do things his way they can help the people in the city now, his hair is blowing in the wind, and the locks by his forehead are obviously clipping into his head. (00:02:42)
Revealing mistake: When R7 goes to plug in to the socket to look up information on Fives, he moves right in front of one arm of a droid charging station in the room which should be in front of him. (00:16:32)
Revealing mistake: When the battle droid commander orders the tanks to stop because they can't go any further into the forest, the fingers of the droid nearest to the camera clip through the wall of its tank. (00:07:49)
Old Friends Not Forgotten - S7-E9
Revealing mistake: When Rex hands Anakin The Box with Ahsoka's lightsabers, his right thigh armour piece briefly clips through his kama twice. (00:12:58)
Revealing mistake: When Ahsoka and Rex walk onto the bridge of the Star Destroyer, in one shot the right part of his kama is partially transparent, revealing his thigh armour beneath it. (00:08:05)
Revealing mistake: When one of the Mandalorians snags Ahsoka's right wrist with a cable, it clips straight through her head and neck in the process. (00:15:46)
Revealing mistake: When Ahsoka and Master Sinube are on their way to Ione Marcy's apartment, Ahsoka's sash keeps clipping through the bottom of her skirt. (00:09:25)
Bombad Jedi - S1-E8
Revealing mistake: When Jar Jar demands that Padmé be released while posing as a Jedi, his ears clip through the back of the hood he's wearing. (00:19:16)
Answer: Dooku never accepted Ventress as his apprentice, as far as I know; he just kept her as his devoted personal assassin. In Phantom Menace, it is stated that there can be only two Sith at a time, to prevent a power struggle in the lower ranks. To accept Ventress as an apprentice, Dooku would have violated that rule.