Kardashian fans claim the reality TV stars have fallen victim to an 'epic Photoshop fail' in their latest campaign for Calvin Klein.
Dozens of eagle-eyed followers noted that Kourtney's right arm appeared to be unnaturally thin - and much more slender than her left - in the black and white photo, which was unveiled this week, the Daily Mail reported.
One posted: "Wow. Who shopped this? They need to be fired. What's with Kourtney's one arm?"
Others noted that Kendall, 22, appeared to have been positioned at an odd angle in front of her sisters.
The photo was taken at a shoot in February, just three months after Kylie Jenner, 20, gave birth to baby Stormi and while Khloe, 34, was still pregnant with daughter True.
One group shot saw Kourtney, 39, Kim, 37, Khloe, Kendall and Kylie, all posing in pieces from the brand's underwear and denim ranges.
However it was the editing that drew comments from Instagram followers after Kim shared the image online.
One fan joked: "Yo Kendall why you fallin' and Kourthey what happened to your hand gurl you ok with the photoshop?(sic)."
Another follower asked: "What happened with Kourtneys arm and with Kendall?", while a third added: "Wish they posted the one before the photoshopping."
"Kourts arm is so photoshopped," another said while one joked: "This picture is kinda weird."
Many more agreed, with a follower writing: "Weird photoshopping of them all together," and one reasoning: "Not everything is epic epic fail maybe. They look beautiful but that editing is all wrong."
Some even claimed that the Jenner sisters had been photoshopped in later, with one asking: "Why is Kendall going sideways," and another arguing: "I think they photoshopped Kylie in Kendall in after."
Trying to explain the oddly skewed snap, one follow theorised: "The sun is reflecting Kourtney's arm i think. Make zoom and tell me what u think. But the photo in general is strange."
Speaking to Mail Online, a spokesperson for Calvin Klein also noted that the appearance of Kourtney's arm was not the result of Photoshopping, but rather a trick of the light during the sun-soaked shoot.
"You can see in the high-res version of that image [that] there are no issues with Kourtney's arm; however, the light is hitting it which makes it slightly less defined," the spokesperson explained.
The higher-resolution version of the image shows a different view of Kourtney's arm - which a much more realistic proportion visible in the original shot.
On Tuesday Kylie posted further pictures of the shoot up, showing off her trim waist in a white sports bra and revealing that the pictures were taken just three weeks after her baby Stormi was born.
Posting a series of snaps from the underwear and denim campaign, Kylie wrote: "This beautiful campaign for @calvinklein by @willyvanderperre just 3 weeks after i gave birth! #ad
"I also love that baby true joined us for the shoot. Such special pics Join Our Family."
MailOnline has contacted Calvin Klein and Kourtney Kardashian's representative for comment.