Pingu Makes a Mistake is the fifteenth episode of Season 3.
Pingu is asked to look after his aunt's egg while she is out with his mother. After a while Pingu starts to get bored until Pingo comes along with his red rubber ball. Pingu has so much fun playing with Pingo, he forgets all about his aunt's egg and does not see it sneak. When Pingo's ball bounces away from them and past the sledge where the egg was sitting, Pingu spots the vacant space and he and Pingo give chase, not knowing which direction the egg went.
At one point, the two young penguins spot the egg, but it is too clever for them and they cannot catch it in time. They follow the path taken by the egg into the igloo of a yellow beaked penguin. They sneak inside to find two eggs: one is sitting on a cot and the other one is standing next to it, rocking from side to side as though it had only just got there. Quickly Pingu and Pingo take the egg next to the cot, not realising that their egg had jumped up onto the cot and pushed the yellow beaked penguin's egg down to the floor. Pingu says goodbye to Pingo and takes the egg back to his aunt's igloo.
When Pingu's aunt gets home, she thanks Pingu for looking after her egg and gives him a lolli-pop as a reward. Then the egg starts to hatch, but when Pingu's aunt sees her new born chick, she is horrified. The chick has a yellow beak, so it is clearly not hers. Enraged the aunt takes back Pingu's reward, but Pingu knows exactly the mistake he made and they go straight back the other mother penguin's igloo. Pingu rings the yellow beaked penguin's doorbell and as soon as she answers the door, she weeps with joy to see her new born chick. Then it is Pingu's aunts turn to start shedding tears when she sees her own long orange beaked penguin chick in the cot. As the two mother penguins cuddle up to their new born chicks, Pingu continues to lick his lolli-pop and thinks what a happy ending it is for everyone.
- Pingu should have been sitting on the egg to keep it warm.
- For Pingu, lessons should have been learned from Pingu Looks After the Egg.