If you don't count the credits appearances, this episode features the least amount of recurring characters in the series' history. Asides from the Simpson family, and Kang and Kodos (that are rather non-canonical characters), only Raphael and Fat Tony (or Fit Fat Tony) appear. Only all the shorts are outranked by this episode in doing so.
This also can be considered the only episode, apart from the THOH specials, to be considered non-canon, owing to the fact that the events are considered rather fantasious.
The last time the credits hadn't featured it characteristic black background at all was on "Treehouse of Horror VI", in which a live action scene covered the entire segment. In this case, still images are covering the segment. If you don't count the mentioned THOH episode because it is a special or is not canonical, the last one had been "Marge On The Lam", in which a still image of the Springfield Police was shown. Coincidentally, both this episode and the above mentioned only feature the Couch Gag.
This is the first episode to be aired in 2015.
Kodos is referred to as male by Homer during the ritual preparation.
Diz-Nee Land is a parody of Disneyland. The fact the company bought out Cosmic Wars is a reference to the fact that Disney bought out Star Wars. Country Storm Trooper Jamboree is reference to Country Bear Jamboree. Jim Jam Bonks Wild Ride is a reference to Jar Jar Binks and Mr. Toad's Wild Ride. Mr. Bugs Slow Ride references this as well.
The scene of them boarding the helicopter is a reference to the end of the Vietnam war where people crowded helicopters at the US Embassy to escape communist North Vietnam.
The fact that Pirates of the Caribbean was revamped was based on complaints that the pirates were drinking and chasing women.
A scene with the UFO references the original Asteroids video game.
The Silver Surfer makes an appearance.
The Xenomorphs from Alien are seen caged at Rigel 7, and reference to the Treehouse of Horror XXV "The Others" segment's Married.. With Children Syfy version.
Homer's "And awaaaay we go!" references Rick Sanchez's catchphrase in Rick and Morty.
Rocky the Flying Squirrel makes an appearance in space with two aliens. He then says "Hokey Smokes! I can't survive in these conditions!" and dies of explosive decompression.
The two billboards are written in Basic, an alphabet from Star Wars. The first billboard says "have your cups lost their suck ? - Suckream", the second one says "Larry H. Zeeblezorp".