What are some plotlines or plotholes that shows a lazy or sloppy writing?

When a mystery has a twist and tries to surprise you with who the villain is with 0 clues or indication that said person was the villain. It cheats you out of both the experience of figuring it out on your own and having that "aha" moment in hindsight as you connect the clues. It is a c**** way to ensure that no one guesses the twist because it is impossible to deduce logically. Worst culprit is *Now You See Me*

FYI, it's rarely the writer and almost always the director and editor. Hell, it could be a producer hammering on the creatives to cut it for time and thus, those plotholes or concerns with reality get tossed. Plus, in many cases, the original writer is long out of the picture by the time production starts unless the director/writer is one in the same or experienced enough to earn a producer credit or whatever.

Are you specifically focused on lazy or low effort writers as the cause? A lot of movie plot holes are the result of script rewrites, re-shoots, or post-production editing. Cutting down for time is another contributor. And there's probably a lot of other causes.

Anytime it turns out at the end of the movie that the main character was the killer and they just don’t know it. I hate being invested in a storyline and then realizing that it’s going to end with the same twist that’s been done two dozen times already. There’s a handful of movies that have done that twist beautifully, and then there’s another 5 movies a year, every year, for the past thirty years, to think they’re being clever and shocking by telling you the scenes you literally just watched on screen didn’t actually happen. It was all in someone’s mind. 

In episode 2F09, when Itchy plays Scratchy's skeleton like a xylophone, he strikes that same rib twice in succession yet he produces two clearly different tones. I mean, what are we, to believe that this is some sort of a, a magic xylophone or something? Boy, I really hope somebody got fired for that blunder

When there's a timer counting down and it doesn't align with the time the movie is passing in real time. Most recently, You can plainly see on John Wick's watch in John wick 4 that he has 8 minutes to get up 222 steps. He's late, but plot armor protected him.

Using the multiverse or time travel to undue all of your decisions. Wrote yourself into a corner? Go back in time and undo it. Killed off a beloved character? They can come back through their multiversal counterpart.

Also the opposite.  When a character just … forgets … I guess a key plot point. 

i love the departed, but why didn't leo just look up mark wahlberg in the phonebook once he realised damon was a rat. wahlberg was only on suspension, it's not like he'd gone into hiding, and, despite being a bit of an a******, leo could be confident he'd vouch for him. always struck me as very weird he decided to go to the rooftop alone.

When there’s a secret evil twin

\- Any car chase where a dinky police car is keeping up with a Ferrari is so totally accurate. \- As for simple plot lines, most shows are in this format: 1. Have a character do something slightly out of the ordinary 2. Spend the rest of the show saying sorry 3. Repeat 4. Profit \- Another easy one is to have the main hero with strongest constitution ever, start crying about something simple. Then have quirky side kick deliver nonsense speech that immediately fixes all crying and restores hero back to pride of humanity. \- The worst one ever: Kill main characters and/or destroy humanity in some apocalyptic fashion that has no way of continuing the series. Then time travel and undo the whole thing.

Project Hail Mary. A weed that eats the Sun... What?