I'd probably rank a couple hundred Pokemon by how cool I think their designs are, could fill the time pretty easy with that. If I acted confident/authoritative enough and added a couple "facts" about how their name is a mix between these two words and how they're based off this kind of bird etc. I could probably pass it off as a lecture.
EDIT: or or or I could lay out my idea for a stop motion Star Fox movie, describe the story, set pieces 'n cast etc. Maybe show some diagrams.
Modern data center infrastructure, the digital transformation and high compute/value workloads Underneath that umbrella I would easily talk storage, network and server architecture with transformational-type workloads (FPGA's, GPU offload, etc.). How and why to pivot depending on the needs, and then I would actually be the one to design the architecture to sell to the customer.
Ok I'll admit, I do 2+ hour presentations every week of the above already. Heading out to do 1 today in about 30 minutes. You'd be surprised how good you get a public speaking when you do it regularly.
International Relations Theory (also applied to real life cases in Europe/Asia)
Japanese economy in the 80s and early 90s
American trade history in regards to economic coercion
Privacy in the digital age
I could fill two hours on healthcare in Canada as well as expense comparisons between the provinces and some explanation for the differences. Plus additional detail on how long term clients are assessed and classified and the companies compensated for their care, though that likely wouldn't be necessary to fill the time.
And probably another couple of hours on health indicators (cancer, illness, drinking, smoking, exercise, etc) across the country and programs implemented to help.
It's crazy what a lot of people don't know. Generally the people who swear off running because of X injury are probably running incorrectly and have bad form. If fixed, overtime, it wouldn't be an issue.
Food, Cooking, and American cuts of meat (too many sub-categories here)
Films of the 80s
Legalization of marijuana and its societal and economic effects
Job training techniques
Traveling on a shoestring while solo
On how the economy in Pokemon is supposed to work when all dads disappear, all moms are stay at home moms, free Healthcare exists, and kids are out robbing each other for spare change while the only company providing proper work is working to do something evil.
Tough question because it isn't clear how polished or interesting this talk should be. Assuming I have an hour to prepare basic notes and pacing and not too worried about quality I could do:
Triathlons (or related endurance events)
Sports (most major)
Geology (Earth Science)
History/Philosophy of Science
Could go into some detail in sub-genres but would feel pretty confident in any of those I listed.