The Message - S1-E15
Other mistake: The characters in this show often use the made-up curse words 'gorramn' and 'gorrammit.' Toward the end of this episode, just as Tracey grabs Kaylee as a hostage, he shouts, "Gorrammit, Mal." The subtitles read: "You're a rabbit, Mal." (00:35:50)
The Great Egg Heist/The Feud - S2-E9
Other mistake: In the Great Egg Heist, when they arrive at the museum, Jimmy gives everyone shishkabob-shaped earplugs for Libby's scream. But in the next shot, if you look at everyone's ears, there are no earplugs. Also, in the next shot, next to Libby you can see Carl putting his hands over his ears. This is impossible because the pointy ends of the earplugs would stab Carl's hands.
Other mistake: In one of the final scenes, Bruce is talking to his father and everyone in the church is "frozen" in a vision. Watch carefully and you can see some people moving slightly.