You can't google something that was personally meaningful to you during a trip, so you [[Taking trip notes|better save it]] when you can.
There's no need to capture easy-to-retrieve facts and figures in your [[Taking trip notes|trip notes]], unless it's personally meaningful to you. For instance, add a factoid if it surprised you—but don't forget to explain why you were surprised in your notes, too.
But don't spend your trip recording random facts like you're writing a book report. Remember, [[Journal for Future You|your audience is Future You]], not anyone else. Future You will want to know personal details and insights from the trip, not generic facts you can easily find in an Wikipedia article. Focus your [[§ Journaling MOC|journaling]] on personally meaningful items.