We have to remember that Wood was just getting started at this point and his work was still inconsistent. However I agree that Harry Harrison had a lot to do with this. And who knows? There may have been other artist friends who dropped by to pitch in. One character sticks out from the rest, Jekyll's friend Lanyon on our page 8. He's drawn so specifically that I wonder if he's a caricature of one of Wood's friends.
As for the Eisner influence, Wood's first comics work was lettering for Eisner. From what I've read he was still working with Eisner at this point. At any rate Eisner was a strong early influence on Wood. Two years after this Wood drew the Outer Space Spirit episodes. It's remarkable how far he'd developed in that short time. Returning to lettering, Wood based his lettering style on Eisner's top letterer Abe Kanegson. Though his style changed over time you could always see a bit of Kanegson in Wood's lettering.