When Toyman escapes from the 20,000 Leagues Under the Sea story, he says the title as "20,000 Leagues Beneath the Sea".
Why were there three simultaneous emergencies if the Legion of Doom had only one device to use to trap the SuperFriends? It should have been three separate emergencies (i.e.: one after the other after the other) in order to pass the device between them and trap each SuperFriend one at a time, like what was done in "The Time Trap".
In addition to the above-mentioned costume goofs, also notice that just before Green Lantern uses his power ring against Luthor and Brainiac after getting free of the pit, his boots are white instead of green.
Green Lantern encases Giganta in a bottle. After he freed Wonder Woman and are about to leave the Alice in Wonderland story, somehow all three of them are inside the bottle. Was that really necessary? The heroes likely would have escaped just as easily if they stayed close to the bottle from the outside.
The SuperFriends' costumes seem to change at various times thoughout the episode: First, Black Vulcan seems to have the full costume that he orignally wore in The All-New SuperFriends Hour when he's observing what happened to the other SuperFriends on the Hall of Justice monitor. The full costume is also seen when he's chained up with Batman, Robin, and Green Lantern. Second, after Hawkman escapes from the giant and then escapes the Jack and the Beanstalk story with Black Vulcan, the green portion of his costume disappears, revealing his legs the moment he lands on the ground. Third, when Batman has his hand on a restrained Sinestro after escaping with Superman, the fingers of his glove are gray instead of blue. And fourth, why is Robin wearing his watch on top of his glove? It should be really underneath it.
Villians appearing without dialogue are Bizarro, Giganta, Gorilla Grodd, Riddler, Scarecrow, and Solomon Grundy.
Aquaman, Apache Chief, Flash, and Samurai make only cameo appearances and have no dialogue in this episode.