Okay so I am a huge Teen Titans fan, so to prepare myself for the big Culling crossover, I decided to go back as far as relevancy can go with the Legion of Super-Heroes so that I can get a good feel for the characters that will appear in this crossover. (Reboot or no reboot). Now since I've been getting my Legionnaire on, I've noticed a little easter egg in Legion of Super-Heroes #1 in the 2010 reboot. That's at least one year before the event happened. Here are the panels with the mention of Flashpoint.
This is in the newly relocated Time Institute when the xenophobia has spread so wide on Earth that they insisted it relocated to another planet. The Legion had it relocated on Titan, home of Saturn Girl. In the new Time Institute, they can now witness all of time on their giant computer screen rather than travel around in their Time Bubbles. As you can see, Usalus wants to explore the event of Flashpoint.
And in this panel, they mention Flashpoint again and also that it happened in 2011. They don't know how it began (which we do), but how it ended. After this, they decide to watch the beginning of the universe, much like Krona did. It ends up destroying the entire Time Institute and eventually the entire moon of Titan. Therefore, we never get to find out what they know about it. I wonder if it reflects in the New 52 version of the series.