I just love the setup of this episode and how a lot happens. I thought it would take the whole time to talk about Cell's origin, but instead they got a lot more put in. We get to see more of the characters converse and get up to speed with everything that's going on. I guess this Imperfect Cell may be my favorite. He just seems like the one who makes actively schemes at this point. I enjoy origin stories, especially ones that don't even cover the whole episode!
Anyway, there's a major continuity error with this. Cell mentions that he was made from the DNA of Frieza and King Kold. He would have been made from Future Trunks' DNA, but they had enough Saiyan DNA already. The thing is, that all happened in the present. In the timeline Cell came from, it would be impossible for Trunks to have killed Frieza, because he isn't from the present! He would have no knowledge of Frieza's and King Kold's defeat. His timeline is at least mostly similar to Future Trunks' and that's not how they died. Of course, it makes even less sense when a later episode features Trunks killing Cell in his own timeline. The Cell Saga still exists, meaning he came from a third timeline.
Speaking of which, this third timeline is now simply forgotten. Now, this doesn't make sense. If Trunks came from a third timeline where he was killed by Cell, shouldn't Cell have gone to the fourth (unseen) timeline? His universe's version of Trunks was going to go back there to talk to his friends, but he wasn't the same Future Trunks that appears in "Dragonball Z", thus that Trunks couldn't have gone to that timeline. Is there a fifth timeline that the second timeline Cell would have gone to if he had killed Trunks? It would simply be impossible for Cell to be in that timeline because he's completely independent from that era. I don't know. Perfect ****!