One quest that I do know of that has a time limit
In Brynnlaw, after agreeing to get the pirate horn for Saemon, only rest if it is daytime, and only do so once. After that, DO NOT rest, as he will disappear and u will have to take the portal instead, i had to go back about 40 days in-game to a previous save and im playing it all over again. If i am wrong and he is there but i cant find plz post on my topic somewhere on the list called 'Where is Saemon'.
It is really frustrating so learn from my mistake, also use The Jaker's idea too incase it happens by accident
'My pantaloons are full of weasels. Inform the Queen, so that she might shoo them away. Here we go 'round the mulberry bush. Go monkey GO!'-Wanev
Have you ever heard any more inspiring or logical words? I sure haven't.