Other mistake: In first episode Wells apologizes for locking up Clarke's dad, then acts surprised when she tells him he got executed, when in episode 3 it's revealed they both assisted in the execution.
The 100 (2014)
1 other mistake in show generally
Starring: Eliza Taylor, Paige Turco, Marie Avgeropoulos, Thomas McDonell
Revealing mistake: At the river to cross over to Mt Weather, the vine used to swing across the river is just a standard rope, camouflaged. You can see it best when Finn recovers it after Jasper has jumped.
Conner: Tell me again.
Raven: You're the most beautiful broom in a broom closet of brooms.