An important moment for the evolving DC Universe - the introduction of its first recurring, still-with-us supervillain in the Ultra-Humanite who does indeed escape at the end of this story. The Ultra-Humanite would return several times, changing bodies along the way until ending up as a macroencephalic white ape. BUT he's really also the prototype for the best known version of Lex Luthor (not to be confused for the red-headed Golden Age original), so it's really the introduction of two Superman villains. And Joe Shuster didn't even get to draw it...
I've used this panel before when discussing the original Sandman's history, but I love it, so here it is again. In Wesley Dodd's first official appearance (the World's Fair comic is out of sequence), he puts a doll of himself to bed before heading out to solve the case of the Tarantula. I love that crazy detail and wish they'd done more with it, in particular in Sandman Mystery Theater.
I've mentioned him, but somehow avoided posting a panel from one of Hop Harrigan's high-flying adventures. Lots of plane action and kind of a fun strip from the looks of it. Who is Hop? Well, he's that aviator fellow who turned up in the original Who's Who, despite never appearing in a DC comic beyond the Golden Age. He DID however star in his own movie serial and a radio series, which is perhaps why the editors decided to use him. That, or they cribbed older "adventure" characters from reprint collections published in the 70s.
Hey, remember the time Jor-El had a frog for a head? Me neither. Mr. Mxyztplk must have wiped it from my mind. Just weirdness.