When Mufasa and Simba are sitting atop Pride Rock, and Mufasa is explaining that the kingdom will someday be Simba's, there is a river to the right (South). When they are walking a moment later, the river has moved to the North.
Oh come on, that's a silly attitude blow.. That's like saying "well since it's a cartoon and anything is possible in the middle of the movie maybe Scar will turn into a male stripper and do a lap dance for Mufasa." Just because it's a cartoon doesn't excuse it from having bloopers like moving rivers or boy cubs changing into girl cubs. (o0o la la!)
It is possible that the river is big enough to stretch the entire length of the pride lands. It's also possible that when some one was laying down the animation cells that it got flipped. Remember at the time all drawings were done by hand and then scanned by a device that would compile the movements in the different pictures; and a background would be at the bottom of the stack only moving slightly as needed.