Knowing your place in an agency is hard. Each agency is different with different hierarchies and systems. It often takes the first week just to figure out what role everyone plays. Your own role, as an intern is submissive, you get told what to do. But I have been at agencies where I have had to bite my lip.
Working in the industry you are working with people who are supposedly much more experienced than you and much more knowledgable and so I often assume that by the time I get something, for example a board for a presentation, to mount, that everything has been checked. This was I figured out after 10 A1 mounted boards found their way to the bin, wrong to assume. After a week at this particular agency I decided that rather than remounting everything after mistakes had been spotted, to have a look for them myself. Whilst I don't want to seem like a know it all, I also don't want to waste my time and energy assuming that they have done their job properly.
As an intern, I usually find myself sitting in on briefings in projects I will be helping out on rather than being briefed myself. In this case, you are sitting in on the ongoing discussions about the work, watching it progress. I was at one agency, where I felt like they were using me as a person who prints and cuts, and goes to Sainsbury's rather than to my full potential, and so it angered me when I could see a project I was briefly helping on, going wrong. I had to bite my lip in case I told the account handler what I really thought of her attempts at copy-writing, and nodded non-commitally.
In highlighting problems that have been missed due to computer error, or because it had been rushed and everyone is busy is acceptable because you are highlighting in order to save time for everyone and it has clearly been a mistake. I found that I was being heralded as having an eye for detail and perhaps I will be remembered for that, rather than for being dim enough to let obvious mistakes run through the plotter wasting time and money, (despite it not being my fault they were there in the first place).
When it comes to creativity, I find, it is best to keep my mouth shut. With a room full of people more eperienced than you, you can rarely criticise. I find it is best to word every thing positively so as to not make it seem like I am arrogant or think I am better than them. I am yet to find an agency that actually takes on board any suggestions I have anyway.
After all, what do I know, I am only an intern.