Death in Paradise (2011)

Episode #1.4 - S1-E4

Stupidity: Richard is hellbent on proving what really happened, but he sits for more than a whole day on a vital piece of evidence (the phone), does not check it, and despite the fact that the victim was reported being in heated arguments with someone on the phone, he asked for no record of the calls (nor checked whose phone was it, which would have required simply inspecting the SIM card), which would have cracked the case instantly.

Sammo ★

Episode #1.1 - S1-E1

Stupidity: The case is made to be this incredibly complex locked room murder mystery, but it is so simply because nobody did a routine check of the phone records of the suspects / one of the victims (if not of the cell tower of the zone). The detectives would have instantly stumbled upon a major unexplained contradiction, since an incriminating call was made.

Sammo ★

Episode #2.4 - S2-E4

Stupidity: It's pure film logic, that a geologist would make a note (to himself, even) and write down together with the element, also its atomic number (not the mass number identifying the isotope, but just the common atomic number, who is always the same regardless).

Sammo ★