Comment on I apologize for nothing by we-were-in-love
Lions actually can purr, but it's more of a...modified growl noise? Small cats have some sort of structure that allows them to purr while inhaling or exhaling, but lions (and some other members of pantherinae) can make a purr-like noise while exhaling.
'Purr-like' does not equal actual purring, though. Unless it's a continuous sound production which alternates between pulmonic egressive and ingressive airstream it's not, by definition, a purr. In the movie it sounded way suspiciously like a housecat. Possibly a mountain lion? I mean, which is fine. It's a fantasy cartoon about talking lions and if they want them to purr in order to be more endearing, power to them.