Culkin pondered why his character Kevin McCallister, a young boy who is mistakenly left behind when his family goes to Paris for Christmas, did not try and seek help from the police when he was attacked by robbers.
The former child star, who is now 37, discussed the plotline during an appearance on The Tonight Show Starring Jimmy Fallon.
“This kid's a really clever kid, right?” Culkin said to Fallon.
“Like, these guys are about to break in, why doesn't he just call the cops?”
He continued: “He makes a master plan, he uses Micro Machines but for real, there's landlines - there are no cellphones but still [he could have called the police].
“I think that's the only thing and I think that's an enormous plot hole.
“I don’t actually spend my days thinking about it, that was just the only one I can think of right now!” Culkin said laughing.
The actor's appearance on the late-night TV show came a day before Culkin hit out at the Oscars on Twitter.
He said he did not want to the 90th Academy Awards that took place on Sunday night because he was too busy cooking ramen and strumming the guitar – all while wearing a tuxedo.
Culkin, who has a new podcast called Bunny Ears, also relished in posting some tongue-in-cheek predictions for Sunday night’s ceremony.
Referring to Best Picture The Shape Of Water, he wrote: “Water takes the shape of whatever container it is in, this entire movie is horse s***. #Oscars.”
Another read: “I firmly believe that @carlyraejepsen's "Call Me By Your Name" should win Best Picture #Oscars.”
This is a reference to the Canadian singer’s hit song "Call Me Maybe".
Culkin was thrust headfirst into the world of showbusiness at the age of four and, at the zenith of his fame, came to be regarded as the most successful child actor since Shirley Temple.
The actor said he had "essentially retired" at the age of 35 and preferred to steer clear of the limelight, in an interview with New York Magazine in July 2016.
He claimed he now spent many of his days painting, writing in notebooks and “whatevering”.
Culkin, who has dropped off the radar in recent years and kept a low profile, said he preferred to go for walks in the early hours of the morning to avoid being recognised by the public.
“I’m a man in his mid-30s who’s essentially retired. I kind of go where the wind takes me a little bit,” Culkin said. “I’ll take walks at two or four in the morning because there’s nobody out on the streets and it’s easy for me to go unnoticed."
Culkin has performed in his band the Pizza Underground, a food-themed Velvet Underground tribute act, becoming its vocalist in 2013. But in July 2016 he revealed the band was parting ways and that the next album would be the last.
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