Factual error: One of the deaths involves a burning candle, a car and a leaking fuel tank, resulting in an explosion. This wouldn't happen. Multiple independent test evidence that petrol/gasoline can't be ignited this way, a flame isn't hot enough. Only the fumes can be ignited, which isn't what happens here, and the tank wouldn't explode anyway.
Continuity mistake: On the third and fourth day, Carter's roommate shows up earlier than the first 2 days. And Tree's suspect tips notebook every day don't reset and the line and erases are the same.
Continuity mistake: When Tree looks at her iPhone it shows the time as 9:23 when the power goes out. Then when the TV is shown the time on that clock is 9:24, when she walks to the TV the time is then 9:31, and then the next view of the clock shows the time back at 9:24.