Amusingly, I often use these things to distinguish cultures or even inspire writing.
1. Not thinking about basic infrastructure. How do they eat? What do they eat? Who takes away the garbage? Who deals with their bodily wastes?
Local cuisine features in many of my series that have a specific time/place stamp; so for instance Italian food in Fiorenza the Wisewoman, Scandinavian/Irish in Hart's Farm, and Romanian/Hungarian in Frankenstein's Family.
"Down the Drain" features a sewage mage. Yes, really. I think about these things.
2. Not explaining why events are happening now. Chances are your story revolves around all heck breaking loose in your fictional world. (Or your fictionalized version of the "real" world.) One major worldbuilding flaw is not explaining why heck is breaking loose now, as opposed to 20 years ago or 20 years from now.
Some of my stories are about all heck breaking loose, but others are about why the heck is getting put back in its corral, or what's going on after the heck has been running loose for decades. These types of stories tend to be carefully situated in the timeline so that you can see how events develop and what influences the characters' choices. Path of the Paladins takes place some years after a major coup among the gods, and concerns how the followers of a deposed goddess are trying to clean up the mess. Tripping into the Future shows the point at which one spacefleet deploys a new and devastating weapon against their enemies, but most of it focuses on the aftermath in which the attacker and the victims are the only ones left. If you look at those closely you can see the clues about "why now."
3) Creating fictional versions of real-life human ethnic groups, that never go beyond one dimension This is a huge problem that tons of creators seem to struggle with. But as a rule of thumb, if you want to have Belgians in your novel, you're going to have to try and create an accurate view of Belgian society. If you decide that instead of Belgians, you're going to have an alien species called the Bzlgizns — who are basically Belgians except they've got antlers — you still have to try and make them well-rounded and as nuanced as possible.
It's actually rare for me to do a monofocal race, and I tend to do that only with reason: such as the hilarious subversion of black/white tropes in Kande's Quest where the evil race is based on Caucasian traits, because somebody said it wouldn't work. Sure it does.
Far more typical of my work is the cultural diversity in the Whispering Sands desert, which is somewhat inspired by Middle Eastern culture. When I started A Conflagration of Dragons I actually sat down and devised six races based on elemental traits, so none of them are humans or dwarves or elves, etc. but all new species. The dragons are actually the seventh sentient race in that world, and I did some cool research on their biology too.
4) Creating monolithic social, political, cultural and religious groups. Everybody in a particular ethnic group agrees about everything. Every member of the ruling class, or the working class, agrees about everything. Every citizen of a particular nation holds exactly the same set of opinions.
*laaaauuuuugh* See above. I'm very persistent about writing diversity. Also my characters have a tendency to run off into the underbrush. I have a KKK group in Waxahachie for Schrodinger's Heroes, run by Chris' asshole cousin Luke -- who has shown up to help save the world, twice. I can't even consistently pick on groups I disapprove of; sooner or later someone does something that doesn't suck.
5) Inventing a history that is totally logical In an imaginary world, the strongest side always wins and the people who are in charge are always the descendants of the people who were in charge 100 years ago. But real life isn't like that — history is full of odd quirks and happenstances, and powerful people often make huge miscalculations that wind up costing them dearly.
I aim for histories that are plausible. That means they always have reasons, but some of those are the same fucking stupid reasons that shaped our history. You have my father, and Mr. Butler's Western Civilization class, to thank for things like The Ocracies and Diminished Expectations where the politics are jumbled and not always pretty.
6) Not really giving a strong sense of place, like what it smells like after it's been raining.
You can spend hours and hours thinking about the history and culture and mores of your imaginary land, and how people interact and the ways that different religious and ethnic groups collide.
Putting boots on the ground is among my strongest suits. See all the ethnic-focused series for that. Also "A Recollection of Smells" deals with this specific issue and the dissonance between memory and the present. I often focus on making the ordinary extraordinary, and vice versa.
7) Introducing some superpower, like magic or insane tech, without fully accounting for how it would change society.
If your pitch is, "It's just like our world, except everybody can turn invisible at will," then you've already failed. Because if everybody could turn invisible at will, it wouldn't be anything like our world.
I have several series that are in-depth explorations of "How would the world change if X?" See The Steamsmith (science is based on alchemy being real), Polychrome Heroics (superpowers are emerging), and Fledgling Grace (God is giving people wings). Contrast this with examples like Monster House where the weird stuff is real, but kept quieter, so the changes it makes are subtle rather than dramatic.