McClane has hopes to reconcile things with his estranged wife Holly at an office (played by Bonnie Bedelia) Christmas party held by her employer at Nakatomi Plaza.
However, as McClane is changing his clothes for the vent, the plaza is hijacked by European thieves led by Hans Gruber (played by Alan Rickman).
And as people are watching this classic action film, some hawk-eyed viewers noticed an error in a pivotal scene.
One of those viewers shared a post shared to the subreddit Movie Mistakes.
"I watched Die Hard for the first time tonight. You can see Karl standing in the background after John just strangled him with the chains. I assume he strangled the stunt double. GREAT Christmas movie, by the way!" wrote u/ChrisGrizz
They were referring to one of the ending scenes in the film when McClane and Karl Vresik (played by played Alexander Godunov), Gruber's second-in-command, got into an altercation.
McClane got several kicks to the face and was shot in the shoulder. However, he managed to wrap a chain around Karl's neck and left him hanging by a chain as the roof of the building exploded and everybody fled the scene.
Despite the supposed editing error, it's worth noting that Karl broke away from the chain and went down to the first floor of the building as the hostages were being escorted out. He threw a blanket around himself as a disguise before he took out his assault rifle in an attempt to kill McClane and Holly.
The effort didn't work in Karl's favour as LAPD sergeant Al Powell (played by Reginald VelJohnson) gave him a fatal shot to the heart.
This isn't the first film, let alone a Christmas movie, where there seemed to be an editing mistake.