I hope there's a lot more of that nervousness shown. His swagger might work in his own film where he's at the top of the food chain, but in a film with demigods and alien invasions, that sort of nonchalance will probably do a disservice to Hemsworth/Hiddleston who need to wear silly costumes while trying to emanate some level of gravitas. Every time I see RDJ in any of these clips, the tension just seems to evaporate for me.
His usual confidence is replaced entirely with false bravado here. He clearly knows that Loki could likely snuff him out at a whim if he chose and is trying to play him.