Continuity mistake: When Obi-Wan says, "Unlike you, maybe he's getting some much-needed rest," he's stroking his chin with his hand. Mid-sentence, the scene cuts to a closer shot of Obi-Wan, and his hand changes position. (00:02:50)
Jedi Crash - S1-E13
Continuity mistake: Anakin sends a ship to dock with Aayla Secura's stricken Jedi Cruiser to pick up everyone who's escaping. When the ship arrives, there are two clone pilots flying it. When Commander Bly gets to the bridge to turn on the deflector shields, one of the pilots has vanished. (00:04:52)
Continuity mistake: Rex climbs onto a barrier of pods that the Jedi built in front of the village to take a look at the approaching droid forces and reports that they have eight minutes tops before the Separatists' arrival, prompting Anakin to order the shield generators put in place. Cut to General Lok Durd and his chief battle droid, who look through binoculars at the distant village, where the barrier is shown as incomplete, with Ahsoka and Aayla still moving pods into place. (00:15:45)
Continuity mistake: After landing the Separatist shuttle at the Lurmen village, Anakin, Ahsoka and Aayla get out and walk around the shuttle, underneath its legs, toward Tee Watt Kaa and Wag Too, as Aayla announces that the Separatists will arrive in moments. When she's finished speaking, the three Jedi have emerged from underneath the ship. The scene cuts to Tee Watt Kaa demanding to know why they came back, and when the scene cuts back to a close-up of the three Jedi, they're walking out from underneath the shuttle again. (00:14:40)
Jedi Crash - S1-E13
Continuity mistake: When the Jedi's ship is in danger of crashing into a star while in hyperspace, there is a brief shot where Rex's kama (kilt) is missing, while Ahsoka is arguing with Aayla about shutting down the ship's power. (00:07:05)
Continuity mistake: When Anakin and his men rush to aid Obi-Wan in the south tower, about half a dozen droids marching inside separate the two Jedi. Anakin begins cutting them up; one of the droids is already crossing the threshold. But when Anakin finally reaches Obi-Wan, the droid who has already entered is suddenly no longer present. The hips and legs falling in before Anakin rushes in come from another droid just outside the door.
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.