The episode was positively received by critics, with praise towards Grant's performance, the pacing, and the setup for the season finale.

Using a TemPad Sylvie stole from Renslayer, Mobius chooses to return to the TVA and reveal the truth about the organization to its employees.

[3] Herron and head writer Michael Waldron executive produce alongside Hiddleston and Marvel Studios' Kevin Feige, Louis D'Esposito, Victoria Alonso, and Stephen Broussard.

[7] Ahead of the series' premiere, Feige had mentioned one of the benefits of exploring the multiverse and "playing with time" was being able to see other versions of characters, particularly of Loki.

Calling the backstory a "thought experiment", Waldron added it was "just so sad" and a "tragic thing" when Classic Loki realizes he is meant to be alone.

Initially, production designer Kasra Farahani had envisioned a "more Salvador Dalí-esque, Dada-esque version" of the Void before settling on an "English moors" styling.

[18] Alligator Loki was created through CGI, with a stuffed stand-in used during filming, which Herron felt was useful for the actors to interact with.

The design of Alligator Loki also shifted several times, after an early version was more of a cartoon style that was "a bit too cute".

Herron was inspired by the teasing of the shark in Jaws (1975) for Alioth, with McDonald referencing volcanic eruptions and pyroclastic flows that feature thermal lightning for its design.

[27] In addition to ILM, visual effects for the episode were created by Rise FX, Luma Pictures, Crafty Apes, Cantina Creative, Trixter, and Method Studios.

[29] An arrangement of the song "Ride of the Valkyries" by Richard Wagner appears in the episode when Classic Loki is creating his Asgard illusion.

The site's critical consensus reads: "An epic penultimate joyride, "Journey into Mystery" pushes the pedal to the floor and lets a gaggle of Lokis do their thing – especially a scene-stealing Richard E. Grant in fine Asgardian form.

"[36] Alan Sepinwall of Rolling Stone said in the comic series Journey into Mystery "anything was possible... which makes it an apt moniker for an absolutely wonderful episode of Loki where the same holds true".

He stated the episode was reminiscent of the series Lost, and believed what made "Journey into Mystery" special was "the way that it explores the untapped potential of Loki himself, in his many, many variations".

Sepinwall concluded his review by hoping for a strong final episode, something he noted had not been the case with WandaVision and The Falcon and the Winter Soldier, though Loki "feels different so far" and "everything up to this point deserves" a good ending.

[5] Giving "Journey into Mystery" an 8 out of 10, IGN's Simon Cardy wrote the episode did "a great job of keeping up the pace set by last week's final revelations.

It displays impressive scale, ranging from stunning apocalyptic threats to tender character moments for both new and returning cast members.

[41] Christine Wada was nominated for Excellence in Sci-Fi/Fantasy Television at the 24th Costume Designers Guild Awards,[42][43] while David Acord, Matthew Wood, Kirsten Mate, Adam Kopald, Steve Slanec, Brad Semenoff, David Farmer, Joel Raabe, Shelley Roden, John Roesch, Anele Onyekwere, Nashia Wachsman, Ed Hamilton were nominated for Outstanding Achievement in Sound Editing - Limited Series or Anthology at the 2022 MPSE Golden Reel Awards.

[44] Herron was nominated for Best Directing in a Streaming Series, Drama at the 2nd Hollywood Critics Association TV Awards for her work on the episode.

[45] Matthew Wood, David Acord, Brad Semenoff, Steve Slanec, Kyrsten Mate, Adam Kopald, Joel Raabe, Anele Onyekwere, Ed Hamilton, Nashia Wachsman, Shelley Roden, and John Roesch were nominated for Outstanding Sound Editing for a Comedy or Drama Series (One-Hour) at the 74th Primetime Creative Arts Emmy Awards.