Character mistake: When Logan tries to use both his and his mom's phones after her fingers were broken by the Man in Black, he throws them in disgust when he finds the SIM cards have been removed. However, every cell is capable of placing a 911 call regardless of whether a SIM card is present or not.
Character mistake: If the nuns in the Abbey weren't real and were created by Valek, why did Valek get one of the nuns to explain to Sister Irene the exact way to defeat her?
Character mistake: During an intermission following Dmitri's revenge after the attempted hit on him, the Chief of staff discusses the data with Dr. Updale. There's a pie chart in the screen in the background, and the segments are; 5%, 25%, 16%, 14% and 50%, which add to...110%. It's not a pie chart, it's a pie and a slice. (00:50:15)
Character mistake: When recruiting Burt to help repel the Graboid attack in the arctic, one of the team members says he's ideal for the job because of his experience hunting them on two continents, a reference to the first two films (Nevada and Mexico in North America) and Tremors 5 (Africa). However, this repeats the mistake in Tremors 5 in overlooking the Argentina incursion stopped by Burt at the beginning of Tremors 3, which gives him experience fighting Graboids/Shriekers/Ass-Blasters on three continents, not two. Burt, himself having overlooked Argentina in Tremors 5, does not correct her. And it's not as if the film is completely ignoring Tremors 3, since it shows the flashback of Burt being swallowed by a Graboid in that movie, which is how he got infected with the deadly parasite killing him here.
Character mistake: Zoe states that Lilly's condition is very contagious and will spread through the camp if they don't go out and get the proper medical supplies they need. She puts Lilly in quarantine... and then proceeds to visit Lilly with no protective equipment. No mask, and even touches Lilly with her bare hands before going back out to the rest of the people. (00:19:20)
Character mistake: Daphne's mother is the one who pressed her husband to tell her the truth, but she is cheering when he says about the basketball anecdote that it was 'real', when later he corrects himself saying "real-ly me, disguised as a mascot." (00:17:25)