After H.W. starts the ceremonial first drilling of the new well, the "walking arm" of this cable-tool rig begins to plunge the bit up and down. The walking arm of a cable-tool rig cannot be used to start a well, as the rigid "tool string" can be forty feet long or more and the derrick tower must be used to drive the bit for about the first sixty feet. Only then can the walking arm be mated to the tool string's cable to continue the bore.
In the "bastard from a basket" scene, H.W. and the interpreter leave after the latter says "I thank God I have none of you in me". It is clear by his lip movement that what the actor originally said was "none of me in you."
In the ending scene with Daniel
and Eli, Daniel starts yelling at Eli as Eli is running down
the bowling alley. As Daniel is throwing bowling balls at
Eli, the first ball is thrown down the left lane, hits Eli in
the foot and ends up in the right lane - no pins have
fallen. The second ball is thrown down the left lane and
is a gutter ball - again no pins have fallen. The third ball
is thrown into the right lane, hits a bucket and
presumably hits no pins. However, as Daniel is chasing
Eli behind the bowling alley you can see that the left
lane now shows only 2 pins still standing.
In the bowling alley scene, Eli is clearly visible placing Daniel's refused drink above the central panel on the paneled divider. After the cut-away to Daniel, the drink is not above the central panel, but above the panel adjacent to the central one.
During the final scene in the bowling alley, Eli pours drinks for himself and Daniel Plainview. Daniel refuses the drink so Eli sets Daniel's drink and an empty glass behind him. As they converse, Eli drinks from his glass until Daniel orders him to stand and say that he is a false prophet. As he stands, Eli takes one last sip of his drink without finishing it and sets it down about a quarter full besides the other two glasses. On the next shot when the glasses are visible over Eli's shoulder, we can see Daniel's untouched drink and two empty glasses whereas Eli's drink was still about a quarter full when he put it down.
When Eli enters Daniel's office to ask about the blessing, as he starts to sit down his hands are starting to tent together, but when the camera changes his hands are at his side and when only after he sits down does he tent his fingers.
When Daniel starts throwing bowling balls at Eli, all twenty pins are standing in both lanes of the bowling alley. After a couple of camera angle changes, nine pins in the left alley are shown knocked over despite Eli nor the bowling balls coming near them.
When Daniel and young H.W. are heading to the Sunday ranch for the first time, a large white camping roll can be seen strapped to Daniel's backpack. When we cut to the shot of them from behind, walking to the ranch, the large white camping roll is strapped to a bag Daniel is carrying in his right hand.
The climactic sequence takes place in 1927 according to the onscreen title. When the preacher refers to not being informed of the recent economic downturn by God, he is referring to the Crash of October 1929.
At the end of the scene when Paul Sunday shows Daniel Plainview the location of the Sunday Ranch on the map, Paul picks up a hat that is quite clearly his own and not Daniel's - Daniel's hat is a dun brown "boss of the plains", while Paul's is grey and more like a wide-brimmed fedora.