The photo, with North West on the left and her friend on the right, shows the children with the straps coming over their shoulders and buckled around their chest.
One person commented: "All I can think about is those car seats... I really hope you were not driving with them buckled in like that."
Further comments included: "Has anyone ever taught you a thing or two about car seat safety?" and "Fix the straps on those babies, come on now".
Jan James, chief of Good Egg Car Safety agreed the straps were too loose but said it's good parents have raised awareness of this issue.
James told HuffPost UK Parents: "It is encouraging that so many concerned parents have picked up on this in the media. The Kardashians live their lives in the media, so they can’t really complain in this instance; especially when it relates to the safety of one of their children.
"Although Good Egg Safety now jointly delivers accredited CPD training for in-car safety, we do not train on seats manufactured in the USA, only European ones so there may be some more issues we are unaware of.
"However looking at the picture of the little girl on the right, it is clear that her chest clip is too low and her straps are too loose.
"If people feel that it’s ‘nit picking’ then they should take the time to see what catastrophic injuries can result from a simple loose harness. Every child has the right to be restrained safely and we are really pleased that so many people have responded to this."
James said children having their straps too loose is one of the most common problems for children's injuries in cars.
"If the straps are loose, the seat doesn't act in the way it's designed to in a collision. Even if a parent is doing 30mph, the impact of that is such that a child could be catapulted out," she added.
"I'm sure all the evidence shows Kim Kardashian adores her little girl, so it's great parents have picked it up to raise awareness of something that parents don't often recognise as an issue.
"We're not pointing fingers, we're just saying it isn't safe and it's in children's rights to be protected."