Character mistake: When Barb introduces herself to Flint, Steve calls her a monkey, and she corrects him saying that she's an "Orangutang", pronouncing the G at the end. But the correct word is Orangutan, with no G sound. Barb would surely know this, as a genius ape.
Character mistake: Flint, despite pronouncing the name of the FLDSMDFR perfectly and berating others for failing to do so in the first film, now pronounces it incorrectly many times, sounding closer to FLDSDFOMNR.