How did Shrek know?
Okay, I've got a potential plot problem in my hands regarding the titular character knowing something that was never made public to him AFAIK.
No, it's not the bit where he and Donkey were heavily implying Farquaad's "short" elements to Fiona, because that was a failed attempt at adult humor that unintentionally created a plot hole on how they knew he was a midget rather insinuation that he... was lacking in bed to put it mildly for those innocent minds who were watching the film. I'm aware of what they were getting at (at least, I'm aware now). While I would hope they would subtly allude to his suspected "compensation for something" in such a way that didn't imply to the younger viewers that Shrek and Donkey knew that Farquaad was a midget despite never getting a clear look at him, I can understand what the writers were trying to do there.
No, what I'm referring to was the climax where Shrek crashed the wedding. When Fiona angrily demanded that Shrek give her a good reason why Fiona shouldn't marry Farquaad, he answered that the latter's only wanting to marry her just so he'd be king and that he's not her true love (which in fact was true). My problem is, how the heck did Shrek know about Farquaad's intention behind marrying Fiona when he never even been present at Farquaad's castle at the time Farquaad made that plan from the Magic Mirror (and thus told his men to organize a tournament). In fact, during that time, Shrek and Donkey were still navigating the swampy woods trying to get to Farquaad's castle so Shrek would get the fairy tale squatters off his swamp. And considering Shrek and Donkey had only just arrived via Dragon at Duloc to stop the wedding, there was no real way for them to have simply done sleuthing around in Duloc when they discovered this.
Can someone please explain how Shrek was even able to know such details? I don't recall Farquaad even making that bit public when making that speech to the Duloc citizenry/knights (even before Shrek made himself public and nearly got himself killed by the knights at Farquaad's behest).