The fifth episode of Rick and Morty: Season 4 is unusual in that it revolves around time travel, a concept creators Justin Roiland and Dan Harmon have frequently said they want to avoid on the series. But as it turns out, a snake-themed Terminator parody isn’t the only way time plays an important role in “Rattlestar Ricklactica.” This episode also seems to clue us into exactly how much time has passed between Season 1 and Season 4.
Reddit user BarnyardCruz points out an interesting detail about this episode. “Rattlestar Ricklactica” is only the second episode of the series to take place at Christmas, with the first being Season 1’s “Anatomy Park.” That would seem to suggest that roughly a year has passed between Season 1, Episode 3 and Season 4, Episode 5.
Source: IGN.com Rick and Morty: How Much Time Has Passed Since Season 1?