The movie focuses on the relationships between Harry, his wife Bess (Sally Struthers), and his mother Cecilia (Ruth Gordon), as well as Harry's failed attempts at contacting Cecilia after her death and his efforts to discredit spiritualism.
The Great Houdinis contains examples of:
- Affair Letters: Harry has an affair with Daisy White (Adrienne Barbeau). A medium obtains some of the letters exchanged and tries to use them against Harry during the congressional hearing.
- Angry Collar Grab: Harry's "audition" in London involves being arrested. He doesn't try to resist, but angrily grabs an officer who tries to arrest Bess.
- Basement-Dweller: At the time Harry and Bess meet, Harry is living with his mother.
- Beard of Sorrow: Cecilia dies calling Harry's name while he's touring Europe. After he gets the news, he falls into a deep depression, during which he grows a beard.
- Blood from the Mouth: Harry coughs blood when a college student punches him before he has time to prepare himself.
- Flashback Effects: When Minnie starts to tell the story of Harry and Bess, the screen ripples.
- Fourth-Date Marriage: By the time they get married, Harry and Bess have only known each other for ten days. She doesn't even know his real name is Erich Weiss until she meets his mother.
- Good Girls Avoid Abortion: Daisy White, the woman Harry has an affair with, mentions that she's had abortions.
- Handy Feet: During his prison escape, Harry uses his foot to pick a lock.
- Jewish Mother: Harry's mother isn't happy with either his career choice or his marriage to a Shiksa Goddess, especially since one of his brothers is a doctor and another is a lawyer. At the beginning of his career, she keeps pressuring him to get a nice job at the tie factory.
- Post-Victory Collapse: Minnie notes that the milk can escape is aptly named, as Harry milks as much drama from it as possible. He stays inside a can full of water for so long that audience members run onstage to free him. After he escapes, he collapses from holding his breath for so long.
- The Power of Hate: Harry's determination to discredit the mediums is the only thing that gets him out of his funk after his mother's death.
- Scenery Censor: During Harry's naked prison escape, his genitals are hidden by the bars of his cell.
- Sleight of Tongue: Bess passes Harry the key to his handcuffs by kissing him.
- Spirit Advisor: One medium who turns out to be the only non-fake says he has an afterlife contact named Fletcher, who can put him in touch with other dead people.
- Spooky Séance: Harry attends one, which he quickly realizes is bogus when his "mother" refuses to speak Yiddish. After Harry's death, Bess attends a different one, with a medium who actually succeeds in making contact with Harry.
- Waxing Lyrical: Bess visits a medium (Bill Bixby) who claims he can contact Harry in the afterlife. He recites the lyrics of the song "Rosabelle," which the two had agreed on as the words Harry would use if he tried to contact Bess from the other side.——
