This isn't a terribly big mistake, but still, I wonder why people don't spend more time correcting their papers.
In this case it's actually in the graphical abstract, and the part that they used color to try to make it more easily understood makes it worse. The blue ethyl group on the diethylzinc becomes the blue methylene in the molecule. First, the ethyl to methylene is a bit of an exotic leap, and even a student should realize, after a moments thought, that's not a trivial transformation. Second, anyone who is familiar with Simmons-Smith chemistry would recognize that diethylzinc plus diiodomethane means zinc carbene, and the ethyl part is not used at all. All they had to do was make the CH2 of the diiodomethane blue to be correct, and it somehow slipped past them. Too bad.
In unrelated news Alexakis and his crazy phosphoramadites have a nifty new-to-me reaction.
1,4-Addition to aldehydes, and enantioselective no less. Is it general? For a highly specialized reaction, some might say yes, but in truth, no it's not. Is it amazing and life changing? If you aren't Alexakis or one of his researchers working on it then no, no it's not.
However it's still pretty neat, and I expect anyone who had done copper promoted 1,4-additions, and/or enantioselective additions will think it's pretty neat.