Suppose you are at an event - maybe a corporate guest speaker situation, or conference, etc. - and a speaker at the podium touts some claim you know to be false (i.e., that “we only use 10% of our brain,”) or maybe even a more dangerous error such as claiming that insulin raises blood sugar when in fact, it lowers it - would you publicly correct the speaker?
I would not correct a harmless misstatement like the first one, because it doesn’t really matter (though I would roll my eyes), but I would probably correct an error like the second one.
Incidentally, this is a message board, not a public speaking event, so I will note that your hypothetical speaker is likely not “at the podium”; they are either on the podium or at a lectern. 
Correcting the first sort of statement (i.e., the wrong-but-harmless one) does little but identify you as a fussy, nitpicking crank. And, if you do this at an event that you’re attending in a work capacity, it’s the sort of thing that might have an impact on your career prospects.
Regarding a more harmful error – in what manner would you be propsing correcting it? Waiting for a Q&A period at the end? Or, standing up and interrupting the speaker with “That’s wrong!”
With respect to the second type of error, if it was a guest speaker at a conference, I would wait until the Q&A period afterwards.
If it was at a presentation in which audience members could ask questions throughout, I would mention it sooner. In both cases, I would be firm but polite, i.e. no “gotcha moment.”
Once called upon, I would say something like, “A moment ago, you mentioned that insulin raises blood sugar. Actually, I believe that’s incorrect. Insulin actually lowers one’s blood sugar.”
That’s how I’d do it, and that’s how I have done it, in similar situations (including at a lawyers’ seminar where the speaker said, incorrectly, that George Washington suffered from syphilis).
You may want to review the subsenses for podium, my friend.
No, robby was correct. This podium word has been so misused that it is now taken by lots of people to mean the same thing as a lectern. So now when you say the conductor is on the podium, there are people who will get a wrong but amusing idea. There’s probably no stopping it, but we can try.
Are you looking at his link or using your own idea of what podium means?
You’re absolutely free to maintain the distinction between the two but that doesn’t mean that the english speaking world is required to bend to your wishes.
If the SDMB were church, instead of shouting “Amen!” or “Preach it!” we’d be shouting “Cite!” 
And “Hi, Opal!”
I think it would be perfectly reasonable to say, in the Q&A, " I may have misheard you but I believe you said insulin raises blood sugar, did I misunderstand?" Which is a perfectly neutral way of giving the speaker the chance to correctly state the true relationship. It also has the added benefit of allowing for the fact that you did mishear or misunderstand and it keeps them onside if you have a follow-up question to ask.
I was at a technical conference, and someone in the audience complained to the presenter about some feature in Windows that they didn’t like (I think the auto-hide task bar, or something like it). The presenter said “Yeah, thats something that Microsoft copied from Apple.”
As a Mac guy, I couldn’t let that slide, and I corrected him very clearly, saying “No, Apple has never done that - Microsoft is 100% responsible.”
Depends on the kind of speaker and the type of event and the kind of error. I went up to a speaker at a teaching retreat once, when they were just chatting with attendees and pointed out that they misused a not-so-common idiom. I wouldn’t do the same at any and all events.
All things being equal, this is probably the best way to handle it if you feel you must speak up. Assume the mistake lay within your hearing, not their speaking, and much of the stress of challenging the speaker can be diffused.
It depends on a lot of things including (but not limited to)
- the type of error
- the type of speech
- how central the error was to the speaker’s main point
- whether I thought the speaker believes in the error or simply misspoke (for example, with the insulin example - if the rest of the speech was on using insulin to lower blood sugar, then I would assume that the speaker got nervous, that their mouth got ahead of their brain, and that the wrong word came out. I’d let that go)
- how the speaker is likely to take such a correction
- how the audience is likely to take such a correction
- my relationship with the speaker
Really, I don’t want to be that guy during a speech. I hate that guy.
No, not unless there was an immediate danger in the statement.
But, I would speak to the presenter as soon as possible and point out the error. He is the presenter and it is her talk, not mine.
Besides, I have been embarrassed recently by telling stories/repeating information that I believe to be accurate only to find that the listener is a recognized expert on the subject. I wasn’t wrong and so wasn’t corrected, but I was giving a layman’s version to an expert. Not a good use of anyone’s time. 
As I get older, the old truism about the IBM person at the meeting makes more and more sense. [For those who can’t recall the 60’s joke: How do you identify an IBM engineer at a meeting? He is the one wearing suspenders and a belt and checks his pants before he stands up.]
???
Moves cursor to bottom of Mac screen and watches dock pop up, then moves cursor away and watches it auto-hide
Are you nitpicking over Apple calling it the dock and not the task bar? Because Apple most certainly was doing that before Microsoft.
Nope.
I’m talking 25+ years ago. Way before OS X.
At that time, Apple’s UI guidelines specifically said that all UI elements needed to be visible - hidden controls were “forbidden.”
And, in an effort to look “cool” Microsoft did some auto-hide thing. I’ll see if I can find out what it was.
ETA: I think it was the Windows '95 taskbar.
Tacky to correct a speaker in public unless there is some immediate safety reason to do so. I got sent to the principal’s office in high school for correcting the computer teacher one too many times.
When I’m arguing in court, and the judge mis-states the law or facts, it’s my duty to correct the judge. I have done that, on occasion, and the judge, if I make the case convincingly, has been glad to have the error corrected. (Especially by me rather than by the Court of Appeal 
)