Toyman mistakenly calls the Jules Verne novel "20,000 Leagues Beneath the Sea" instead of "Under the Sea"
Hawkman climbs the beanstalk trying to catch up with Toyman instead of simply flying.
Batman claims that he, Robin, Green Lantern & Black Vulcan are in an escape-proof trap.
Batman tries to rewire the computer to reopen the trap door but the trap door never closed, they were simply in a hole in the floor.
Even if Batman and Robin couldn't immediately get out, Black Vulcan and Green Lantern could simply fly out of it and stop Luthor and the rest of the Legion.