The only references I didn't get were the ones on page 8 above the Pingu reference.
What the hell would I even google to find those? "guy on bike with raccoon?" "japanese beaver mascot?"
Trust me, that was definitely an issue for me when writing the references bit (especially King ExKaiser since "lion mecha anime" just kept coming up with Voltron). I eventually got the beaver and otter ones by searching for their Japanese names with キャラクター and ExKaiser by revising my search to "mecha with lion on chest".
And rest assured, this isn't the only one of Unno's doujins that's full of ancient anime references.