The Billund-based company wrote in its current members magazine that a human error in 2015 resulted in the recall of 129,000 Lego sets.
The sets, which included such popular lines as Lego Star Wars and Lego Creator, were supposed to include dark grey Lego boxes but were instead packed with light grey pieces.
The mistake was traced to Lego's Billund factory and it was discovered that an employee had attached the wrong colour label to a colour tube.
Although Lego discovered the error before the sets hit retail stores, the company had to call in vacationing employees from the Czech Republic and Hungary to repack the sets.
Lego then invested 400,000 kroner in a project meant to avoid similar mistakes in the future by changing the lighting levels in the factory and allowing workers to pre-print the colour labels.
The entire episode cost The Lego Group 10 million kroner, according to the company. That sum is peanuts for a company that enjoyed record revenues in 2016, at 37.9 billion kroner ($5.2 billion, €5 billion). Lego's net profit was 9.4 billion kroner.
The employee involved in the mishap did not face any consequences.