Working as a school board auditor, he threatens to cut the glee club out of the budget, bitter at never having attained his own show-business dreams.

The episode features cover versions of seven songs, four of which were released as singles, available for digital download, and three of which are included on the soundtrack album Glee: The Music, Volume 3 Showstoppers.

Club all deemed it one of the best episodes of the season, while Aly Semigran of MTV, Entertainment Weekly's Tim Stack and Raymund Flandez of The Wall Street Journal praised the musical performances.

Bryan Ryan (Neil Patrick Harris), a former McKinley High glee club member, arrives as an auditor from the school board.

Glee club director Will Schuester (Matthew Morrison) convinces him that it is not too late to pursue his dreams and sings "Piano Man" with him.

Bryan decides not to cut the glee club, and even presents them with new costumes and sheet music, but changes his mind when cheerleading coach Sue Sylvester (Jane Lynch) announces that Will landed the lead role.

After Bryan's discouraging speech, Tina (Jenna Ushkowitz) retrieves Artie's paper from the trash and learns that his biggest dream is to become a dancer.

[1] In October 2009, Michael Ausiello of Entertainment Weekly reported that 20th Century Fox, the studio behind Glee, had approached Joss Whedon about directing an episode during the show's first season.

Asked by Ileane Rudolph of TV Guide whether the episode would feature songs from Buffy, or his 2008 musical Dr. Horrible's Sing-Along Blog, Whedon replied: "I would have to say a resonant 'no way.'

He acknowledged his proclivity for killing off fans' favorite characters, jesting that he planned to murder Principal Figgins (Iqbal Theba).

Online commented on Whedon's tendency to work repeatedly with the same actors, and hoped that Dr. Horrible star Neil Patrick Harris might appear in the episode.

[8] Recurring characters who appear in "Dream On" are glee club members Santana Lopez (Naya Rivera), Brittany Pierce (Heather Morris), Mike Chang (Harry Shum, Jr.), Matt Rutherford (Dijon Talton) and Jesse St. James (Jonathan Groff), astronomy teacher Brenda Castle (Molly Shannon, appearing alongside her Kath & Kim co-star, John Michael Higgins), and Vocal Adrenaline coach Shelby Corcoran (Idina Menzel).

Maureen Ryan of the Chicago Tribune deemed "Dream On" a "highly enjoyable", "emotionally satisfying" episode, and possibly her favorite since the pilot.

[22] Lee Ferguson of CBC also called "Dream On" one of his favorite episodes of the season, commenting that: "NPH easily outperformed some of the other recent celebs (including Molly Shannon and Olivia Newton-John) who've stopped by the show", and hoped that his character would return in the future.

"[29] Raymund Flandez of The Wall Street Journal called Michele and Menzel's number "one of the most touching duets in the show so far", stating: "the vulnerability they both convey is stunning in its simplicity and perfection.

He rated the songs performed "B+" through to "A" and called "Safety Dance" one of his favorite moments of the episode, deeming it a "joyous, huge performance—definitely one of the most elaborate numbers the show has done before.

"[31] Blair Baldwin of Zap2it wrote that while the "Dream On" performance began perfectly, Harris "killed the song" with an "ear-wrenching" lead-in to the chorus.

He felt that the musical numbers "failed to really resonate", and called Harris' character "amusing in theory" but ultimately "one-note" and lacking in impact, with a storyline that "fizzled out".