Well, Mahabharat is passed on from generation to generation in a form of story. So, there are many additional stories added by people here and there. Some of them are:

Parshuram and Bhishma fought because of Amba because she complained to Parshuram about his disciple. Bhishma had won after she used Pashupatastra on Parshuram or some other weapon...

Gandhari was a manglik. Manglik is something that is related to Vedic astrology, which is quite more accurate than the Greek one. Manglik means that a person's first spouse will die. So, that person is then married to a goat, sheep, tree or anything else and then the first spouse is killed or cut down. Thus, according to this story, Dhirtarashtra was her second husband because she had married a goat first. So, when he came to know about this, he got angry and imprisoned the hundred sons of Subala. Subala and his sons knew that Shakuni loved his sister the most and was the most evil one among them. They all used to get one fist of rice everyday. So, they used to give their rice to him and Shakuni somehow survived through one fist full of rice everyday. He made dice out of the bones of Subala. That's why the dice obeyed Shakuni. When Dhirtarashtra came to know that only Shakuni had survived and how he loved his sister so much, he decided to keep Shakuni as a pet. Now, this story has so many potholes because Shakuni didn't have any brother. Besides, he also had a wife at home and he was the king of Gandhar too. He wanted the Kauravas to be dead not for his father but because of the way Gandhari was abused time and again and Bhishma, Satyavati, no one said anything against Dhirtarashtra except Vidur, Kunti, Pandu and some other people. He had thus planned who his enemies were.

Then there is this story that Pandu's last wish was that his sons would eat his brain after he dies because he wanted his sons to have some part of himself. Sahdev had eaten three bites because he was too young and naive but others dared not to. That's why he knew the past, present and future. Now, it's not true again because there is no story to prove his knowledge about past, present and future. He never showed that knowledge. There is one story though where Krishna threatens him that if Sahdev tells about the pending war or Draupadi's cheerharan (unrobing) to anyone, all of their race will turn to ash in an instant but let's think about this. He would rather end his entire race than let Draupadi be humiliated or killing his race with his own hands. That's worth thinking over. So, this story is both gross and incorrect on so many levels.

Then, the biggest understanding about Draupadi was that she had five husbands. Just because her name was Panchali doesn't mean that she had five husbands. She got that name because of her mahajanapad and not because she had five husbands. She was only married to Yudhisthir. 80% of the Mahabharat is wrong and adulterated and so are the stories which talk that she is the wife of all of them. Why? I will tell it later...

Then there is this story that Karna and Draupadi loved each other. This is wrong and was done around the second translation by the Britishers to harm the dignity of Draupadi and even added some stories but she never felt anything about him and other stories about her feelings for her husband or rather husbands prove this.