I know most of these were already covered, but I just had to post some stuff that bugged me about this episode. All-in-all it was a good episode though.
First, kind of strange hearing the LightSpeed Vanguard switched to the Legion of Super Villians. We didn't even get to hear how. This would be good potential for a flashback story or especially for the comic book.
Second, the way Brainy acted like time travel technology was standard issue and Phantom Girl would just happen to have it on her was disconcerting, since none of them were carrying any such technology. I liked what one poster wrote about the possibility of her accessing another dimension for safe-keeping to pull the technology from. Would have been better if they had not treated the technology as standard issue.
Third, Clark must have really extraordinary hearing. He heard the crack about being skinny even before they materialized, so he heard it from the past. Would have been better if the time bubble would have been visible first.
Finally, I really wanted to know who Superman was talking about when we was giving that talk to Superman X. I felt like they specifically didn't name any names. I wish they'd go back and elaborate on this in a future episode. I didn't think it was Timberwolf. I did think of the Superman meeting Batman thing, but not the version from the Superman and Justice League cartoons as someone else mentioned, though this could be likely. I thought of the Batman episode that aired just after Legion. In that episode, it was Superman who was reluctant to join the Justice League and Batman who was trying to convince him. I wonder if Legion writers have any contact with Batman script writers and knew the episode following theirs or if it was just a coincidence. Anyway, felt it was very vague. You could have filled in the blank with almost anyone. I would have preferred if Superman had named names.
I kind of overlooked the poor fighting on Tekron-Galtos and needing Superman X to turn the tables. They didn't want to Duo Damsel to get hurt and once she was safe and they were freed by Superman X, they could give it their all again. As someone else suggested, one of them should have tried to free their team members first, but again, if Duo Damsel were in immediate danger, they might have all surrendered like the rescue party did.
Other than that, enjoyed the episode. Characterization was great as was pointed out by others and lots of action in this one.