They refuse to count a couple of them, making the amount of episodes inconsistent.
The reason for this is a lost episode from season 1.
Finding details about this missing episode is difficult, no one who was working on the show at the time likes to talk about it. From what has been pieced together, the lost episode was written entirely by Peter Browngardt. During production of the first season, Peter started to act strangely. He was very quiet, seemed nervous and morbid. Mentioning this to anyone who was present results in them getting very angry, and forbidding you to ever mention it to Peter. I first heard of it at an event where Peter Browngardt was speaking. Someone in the crowd asked about the episode, and Browngardt simply left the stage, ending the presentation hours early. The episode's production number was 1019-000a, the title was Pizza Steve's Revenge. The episode labeled 1019-000a, Uncle Grandpa (the episode's title), was made later and given Pizza Steve's Revenge's production code to hide the latter's existence.
In 2012, 3 months after the final episode of Uncle Grandpa was done, there was a reunion party for all employees of Cartoon Network. The president of Cartoon Network invited all employees to watch the first episode of Uncle Grandpa. As he opened his computer to view the video file, he saw the episode entitled "Pizza Steve's Revenge." He thought it was a "sequel" to "Uncle Grandpa" the pilot episode, so he clicked on the play button and went to make popcorn.The episode began with the impressive intro, but it played at lightning speed and stopped at the title card. The episode started off like any other episode, but had very poor quality animation. If you've seen the original animation for the pilot episode, it was similar, but less stable. The first act was fairly normal, but the way the characters acted was a little off. Uncle Grandpa seemed angrier, Mr. Gus seemed depressed, Pizza Steve seemed to have genuine anger and hatred for Uncle Grandpa. It started with Uncle Grandpa, and Pizza Steve. They were walking down a road, while in the background weird moaning could be heard. It cuts to a close up of Pizza Steve's color-inverted face with a knife in his hand and he stabs Uncle Grandpa in the stomach, causing him to fall down and limp with a blood trail following him. Uncle Grandpa became inverted, as a news-reporter came over and said "Oh no, Pizza Steve, Pizza Steve". Then, it cut to Pizza Steve killing people by throwing knifes at them and killing them. Then it showed Uncle Grandpa and the peoples' ghost crying blood, as Pizza Steve laughed in a loud voice, not like his usual voice.
Then it said "THE END" and "R.I.P UNCLE GRANDPA", then the episode ended with gibberish text and "THANKS FOR WATCHING UNCLE GRANDPA" and the "Cartoon Network" logo.
When the video ended, the phone suddenly rang. When the president answered it, he heard Pizza Steve's voice saying, "Don't come to the studio, or you will be coming with me to Hell." After he hung up, the president suddenly found that he was not alone; Pizza Steve was now right in front of him with a knife in his hand. Pizza Steve then threw the knife right at the president. At that moment, the president woke up. It had all been a horrible dream. However, the next day, he still told everyone to leave, as Uncle Grandpa was now canceled. He had been muttering something about the last episode featuring the death of Uncle Grandpa, and that it had been done with a real corpse. Nothing else happened after that.