Check for Provide an accessible overview (MOS:INTRO): Done
Major Point 1: Plot "The series follows the adventures of Finn ... with his family and his dog, Jake on a farm." (not a concise summary of the Plot section, few important points like events after the "wish" and the "crown" are not in the lead, while "Finn is then warped ... Jake on a farm" is not in the body.)
Major Point 2: Production "The episode was written and ... and Cloris Leachman as Farmworld Marceline." (summarised well in the lead)
Major Point 3: Reception ""Finn the Human" was watched by 3.435 million viewers and received largely positive critical acclaims, with many critics writing that the episode was a creative challenge." (not a concise summary of the Reception section)
Check for Relative emphasis: Done
Major Point 1: Plot "The series follows the adventures of Finn ... with his family and his dog, Jake on a farm." (the lead gives due weight as is given in the body)
Major Point 2: Production "The episode was written and ... and Cloris Leachman as Farmworld Marceline." (the lead gives due weight as is given in the body)
Major Point 3: Reception ""Finn the Human" was watched by 3.435 million viewers and received largely positive critical acclaims, with many critics writing that the episode was a creative challenge." (the lead does not give due weight as is given in the body)
Short paragraphs and single sentences generally do not warrant their own subheading. Paragraphs should be short enough to be readable, but long enough to develop an idea. (WP:BETTER)
Merge Background and Events sections to fix the short paragraph "In the fourth season finale, Finn and Jake are tricked by the Lich—disguised as the hero Billy—into opening a portal to the multiverse by using the Enchiridion. After the Lich passes through, Finn and Jake give chase, and a mysterious new reality is created.".
Fix ""Finn the Human" first aired on Cartoon Network ... "Jake the Dog". the episode ... at the time of the airing." in the Reception section. There is also a 1a issue: the should be The.
Fix "After being pulled into the portal, ... into the reality created by his wish." in the Events section.
Check for Standard appendices and footers (MOS:APPENDIX): Done
"really fit in the Adventure Time world".[6] (Check on source 6, successful, "With Finn and the viewer experiencing an alternate timeline, I thought it would be cool to design some characters that didn’t really fit in the Adventure Time world.")
"a little bit jarring" ... [6] (Check on source 6, successful, "The tone is I think, a little bit jarring, so I was worried that viewers would be put off by it")
"loosely inspired by the Japanese manga series Fist of the North Star.[6] (no end quote after inspired) (Check on source 6, successful, "heir look was loosely inspired by the Fist of the North Star. Pretty much, everything I do is loosely inspired by FOTNS.")
"Finn going insane" ... [6] (Check on source 6, successful, "And Finn going insane was I think all Rebecca. ")
"a dense première that evokes nearly all aspects of this series."[4] (Check on source 4, successful, "The Dog” is more focused on humor and relationships, and the result is a dense première that evokes nearly all aspects of this series.")
"an action-packed, mythology-heavy chapter" ... [4] (Check on source 4, successful, "“Finn The Human” is an action-packed, mythology-heavy chapter, ...")
"nice change of pace".[4] (Check on source 4, successful, "This two-parter is a nice change of pace, but it’s nice to be back in the rainbow-colored world of Ooo.")
"irreverent and narratively engaging".[8] (Check on source 8, successful, "... more clearly represents the progress of the medium: Irreverent and narratively engaging, ...")
"the ideal testament to animation's glorious pliability in an commercial arena otherwise defined by restrictions."[8] (Check on source 8, successful, "... it's the ideal testament to animation's glorious pliability in an commercial arena otherwise defined by restrictions.")
"sad subtext" ... [8] (Check on source 8, successful, "... toys with an incredibly sad subtext: The world has been destroyed in something called The Great Mushroom War.")
"deny the bad vibes their surrounding world invites" ... [8] (Check on source 8, successful, "Through friendship and playtime, the characters seemingly deny the bad vibes their surrounding world invites.")
"cheery songs and vibrant artwork" were some of the series strongest points.[8] (Check on source 8, successful, "The cheery songs and vibrant artwork remain sincere while challenging the backdrop at the same time.")
"interesting creative challenge".[8] (Check on source 8, successful, " provided an interesting creative challenge for Ward and his team: a prolonged running time of half an hour, which basically amounted to a double episode.")
Check for Likely to be challenged: Done
Check for Contentious material about living persons (WP:BLP): NA
Image 1 (Ming-Na 4.jpg): This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. This version permits free use, including commercial use. Hence this image complies with The license must permit both commercial reuse and derivative works.
Image 2 (Kumail Nanjiani by Gage Skidmore.jpg): This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. This version permits free use, including commercial use. Hence this image complies with The license must permit both commercial reuse and derivative works.
Check for copyright status: Done
Image 1 (Ming-Na 4.jpg): Free.
Image 2 (Kumail Nanjiani by Gage Skidmore.jpg): Free.
Caption: "The episode guest starred Kumail Nanjiani (left) and Ming-Na Wen (right) among others." succinct and informative
As per the above checklist, the issues identified are:
The lead does not provide an accessible overview. Major Points like the Plot and the Reception are not the concise summaries of their respective sections.
The lead does not give relative emphasis to the Reception as is given in the body.
Short paragraphs generally do not warrant their own subheading. Merge Background and Events sections into the Plot.
Paragraphs should be long enough to develop an idea. Fix other short paragraphs.
No inline citations for the direct quotations: "never even ever existed." and "mutagenic bomb".
No end quote "loosely inspired by the Japanese manga series. It should be after inspired as per source 6.