When Eko returns to his brother's church the first time, he has a quite large silver teardrop-shaped earring in his right ear. When his brother walks outside to greet him, the earring is in his left ear.
When Eko smashes the Virgin Mary statue, you can see the bag of heroin fall off the table in a short clip, but in the next clip, it is centered on the table.
The wreck that Eko's brother is in is not the same one he took off in. When Eko leaves the bloody hand print inside the plane, the wall is an off white with a mark that looks to be left by a piece of tape. When Eko finds the hand print in the wreck, there is now a red stripe along the opening, and no tape mark.
Near the end of the episode, Ana Lucia is on the beach starting a small fire for herself. There is a woman behind her who is standing still at the beginning of the shot, waiting for "Action" to be called.
When Eko recites the 23rd Psalm, he incorrectly says, "Yea, though I walk through the shadow of the valley of death...." Charlie recites it incorrectly as well. The correct verse is "the valley of the shadow of death...."
On Eko's prayer stick is written 'Revelations' - likely a reference to the last book of the Bible - which is 'Revelation' - singular, not plural.