Character mistake: When Commander Cody says "We'll get right on it", Obi-Wan responds with "No, Captain", calling him by the wrong rank. (00:05:18)
Character mistake: After Anakin says to use the walkers (AT-TEs) as boarding vessels, Rex calls the first one an AT-AT (a vehicle that does not even exist at this point in-universe) while ordering a battalion of clones into it. (00:04:10)
Character mistake: When Queen Neeyutnee thanks Jar Jar at the end, she erroneously refers to him as "Senator" Binks (he's a representative). (00:21:46)
Character mistake: When Jesse says that he's "really not liking this", Fives calls him Hardcase when he responds with "don't get an itchy trigger finger." (00:15:35)
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.