Moondram Pirai depicts a young woman whose mental state regresses to that of a child following an accident. Sexuality and the repression of desire are dominant motifs, similar to Balu Mahendra's previous film
Moodu Pani (1980). The film also explores the possibility of unresolved sexual tension between the protagonists. When asked about the reason amnesia was chosen for a disability, Mahendra said the disorder is used as a camouflage and as an excuse to portray relationships in the film. Film critic
Baradwaj Rangan finds the sequence where Cheenu narrates the story of
the Blue Jackal to Viji to be a distant echo of the arc negotiated by Cheenu: "He is, after all, a nobody [like the jackal] who, through a salubrious twist of fate, becomes the ruler of a woman's life, until he is restored, at the end, to the nobody he was, a fraudulent claimant to her emotions." In his book
Dispatches from the wall corner: A journey through Indian cinema, Rangan says that although Haasan is inspired by
Marlon Brando, the scene where Haasan burns himself while cooking and vents his anger on Sridevi, is reminiscent of the acting style of
Marcel Marceau. In another book of Rangan,
Conversations with Mani Ratnam, he states that in the scene where Cheenu enters Bhagyalakshmi's room in the brothel, there was fumbling and embarrassment, whereas in another Haasan film
Nayakan (1987), his character, Velu Nayakar, behaves as if he has visited a brothel before.
Nayakans director
Mani Ratnam replied that the two scenes are very different from one another and that it "can't be played the same way". Rangan called
Moondram Pirai "The apotheosis of [Balu Mahendra's] art". Nandini Ramnath, writing for the website
Scroll.in, noted that
Moondram Pirai contains elements common in Balu Mahendra's other films: "realism, evocative and naturalistic cinematography, strong performances, and psychosexual themes that drive the characters to make unusual and often tragic choices." Hari Narayan of
The Hindu said Cheenu "looks like a melange of John Keats|[John] Keats' tragedy and Sigmund Freud|[Sigmund] Freud's
psychoanalysis." Narayan explains the idea of Cheenu keeping Bhagyalaskhmi with him not only as an act of sympathy and love, but also with the intention to preserve her like a portrait. Narayan also states that when Bhagyalakshmi recovers her memory and forgets him, Cheenu is hesitant to come back to his quiet existence, realising that in reality, dreams feel like its
antithesis. Malathi Rangarajan of
The Hindu considers the usage of a railway station in the climax scene to reflect the Tamil cinema trope of "Turning points, crucial interludes and significant twists" taking place in such places. According to S. Shiva Kumar of
The Hindu, the climax of the film was a clear allusion to Mahendra's then wife
Shoba's death. Thyagarajan denied this, saying Mahendra narrated the story to him much before, and Shoba's death occurred only once the project was being finalised. == Music ==