The film's non-diegetic music was scored by American jazz pianist Herbie Hancock, and the English rock group The Yardbirds are seen performing "Stroll On".

The plot was inspired by Argentine-French writer Julio Cortázar's 1959 short story "Las babas del diablo", which was later retitled "Blow-Up" to tie in with the film.

Blowup has influenced subsequent films including Francis Ford Coppola's The Conversation (1974) and Brian De Palma's Blow Out (1981).

As he leaves the studio, two teenage aspiring models ask to speak to him, but he brushes them off and drives off to visit an antique shop near Maryon Park.

Thomas examines a blurred figure on the ground under a bush in the blow-up, which he suspects is the dead body of a man shot by the gunman.

At a drug-drenched party in a house on the Thames, Thomas asks a cannabis-addled Ron to come to the park as a witness, but cannot convince him of what has happened.

Thomas watches a mime troupe perform a mock-tennis match at the park, and picks up the imaginary ball and throws it back to the two players when asked.

Uncredited members of the cast include Tsai Chin as Thomas's receptionist, Susan Brodrick as the antiquarian, Ronan O'Casey as Jane’s lover/victim in park.

As Thomas persists, his quest leads him initially to question his technical mastery over the "hidden truth" recorded by his camera, then toward a confrontation with the realities of his life of "material advantages, gained at the expense of ideals".

Indeed, the absence of a solution is part of the point: life's uncertainty ... the true suspense resides not in the mystery of the photographic blow-ups, but in the instability of Thomas himself.

[14] According to Gow, "a mystery without a solution is instrumental to the theme of disorientation" which is sustained until the final moments of the film, in which Thomas fails to resolve the contradictions and ambiguities that arise from his investigations and his own life.

[17] Gow considers two interpretations for the ending: Since Blow-Up is not resolved happily, but rather in a total surrender to fantasy and consequently to oblivion, we can take it either as an exhortation to come to terms with reality, or as a cautionary tale in which the pursuit of material gain is a threat to humanity.

Other locations included Heddon Street[28] (where the cover of David Bowie's album The Rise and Fall of Ziggy Stardust and the Spiders from Mars would later be photographed)[29] and Cheyne Walk in Chelsea.

[citation needed] The scene in which the Yardbirds perform "Stroll On" – a modified version of "Train Kept A-Rollin'" with new lyrics – was filmed in a replica of the Ricky-Tick club at Elstree Studios in Borehamwood, Hertfordshire from 12 to 14 October 1966.

"[31] O'Casey had previously told this story to Der Spiegel in 1967, where he stated that Dyson Lovell played the part of the murderous lover.

[33] Thomas drives a Rolls-Royce Silver Cloud III 'Chinese Eye' Mulliner Park Ward Drophead Coupé owned by DJ and television presenter Jimmy Savile.

Only about one hundred coach built Silver Clouds IIIs were made with the unique slanted headlights, and it remains an iconic element of the film.

The film's critical and commercial success played a major role in the abolition of the Production Code and its replacement with the MPAA rating system shortly thereafter.

[39] Bosley Crowther, film critic of The New York Times, called it a "fascinating picture",[6] but expressed reservations, describing the "usual Antonioni passages of seemingly endless wanderings" as "redundant and long"; nevertheless, he called Blow-Up a "stunning picture – beautifully built up with glowing images and color compositions that get us into the feelings of our man and into the characteristics of the mod world in which he dwells".

[40] The conscience of Thomas in Blow-Up is not troubled by any sense of obligation or responsibility to the girl [Vanessa Redgrave as Jane] he has photographed in the park.

[14] According to author Thomas Beltzer, the film explores the "inherently alienating" qualities of mass media, where "the camera has turned us into passive voyeurs, programmable for predictable responses, ultimately helpless and even inhumanly dead".

"[9] Roger Ebert described the film as "a hypnotic conjuring act, in which a character is awakened briefly from a deep sleep of bored alienation and then drifts away again.

Yet, out of the context, it's just a broken piece of a guitar [...] the important point here being that meaning, and the construction we put on reality, is always a group social function.

[54] In 2017, the Criterion Collection issued the film on Blu-ray and DVD, featuring a 4K remaster from the original camera negatives, in addition to new bonus materials.