"Rick and Morty" Season 2 ended a few weeks back, leaving behind major cliffhangers for Season 3. Though the show has been renewed for another season before it ended its Season 2 run, there is no specific release date yet for Season 3. However, reports suggest that the Season 3 premiere date of the show was actually hinted in the Season 2 finale post-credits sequence. Meanwhile, show creator Dan Harmon has "promised" an appearance from Mr. Meeseeks in Season 3.
According to International Business Times (IBT), though the Season 3 release date of "Rick and Morty" has not yet been announced, the post-credits scene of Season 2 finale episode actually hinted when the show will come back. In the sequence, Mr. Poopy Butthole can be seen talking to a pizza delivery boy, asking him about the show's Season 2 finale and the major cliffhangers. The video then ends with him saying, "Tune in to Rick and Morty Season 3 in like a year and a half or longer to see how we unravel this mess."
Master Herald points out that this would mean that "Rick and Morty" will be back for Season 3 in March 2017. According to the site, this is highly likely since the show does not have a regular schedule unlike other TV series. It pointed out that the show's Seasons 1 and 2 actually had a gap of about one year and three months, which is not far from the "year and a half or longer," which Mr. Poopy Butthole said in the clip.
Meanwhile, show creator Harmon previously talked to The Hollywood Reporter about the next season of the show, and he said that he'll make sure that Mr. Meeseeks will be featured in Season 3 of "Rick and Morty."
"I'm going to make that a personal promise to myself. I'm going to force Mr Meeseeks into season three," he said, as quoted by IBT.