Do you ever find yourself getting pulled off the subject matter you have prepared to present?
I do -- it seemed to be happening a little too frequently.
In the organization I work in, the culture allows directors and above to interrupt the flow and ask questions whenever they have one or they correct details or point out where a another term would be more appropriate.
This can really ruin the flow of the presentation, and often the point is not really relevant or answer is actually contained later in the slides.
So how to handle this?
Start with a clear outline or agenda of what you will be covering. If they pay attention, this may help.
Credit
Stop and credit the person's knowledge -- "Thank you for that comment, I'll note that." Then continue -"The point of this slide is ___ -- is that clear?"
Pause
Pause and then continue -- this is a good technique if the interruption is especially picky. Silence can also be powerful, accompanied by a direct look. (Try not to think 'you jerk' while you are doing it)
Slow down
Make sure you are projecting your voice - a clear voice sounds more confident and interesting
Keep to the content -- use "this" or organization's name, not "I" or "Me"
Example: The point vs, my point -- this separates the content from you personally
Don't get upset -- the point is to get to an agreement or conclusion, not to win or be perfect.
Sometimes a derailing question can lead to a better outcome, and in that case, you may have to go with the flow.