Patzer

Whenever the newly-born Warlock screams his fillings are visible.

Clear stunt person on the motorcycle at the end, especially when it slides.

Kenny very dramatically makes a point of carefully tasting the bloody rain and jumps with surprise to find it tastes like blood. However, he very clearly has the bloody rain already in his mouth. Kenny's teeth are actually already red with the bloody rain before tasting it.

When Charles Hallahan, R.G. Armstrong and Steve Kahan are sitting at the table in the basement and right after Armstrong says "The Warlock is here" you see that Charles Hallahan's lips are moving but nothing can be heard. Scene starts at around 21 minutes 20 seconds.

When Warlock is pushing a rock onto Sam, you can see crew behind the rock along with cameraman.

From dialogue: The devil is released when "first there is a lunar eclipse and six days later there is a solar eclipse". Lunar eclipses always occur during a full moon, solar eclipses during a new moon. Those can never be only six days apart.

At the ending of the first film, the Warlock learned the true name of God, which spoken backwards, would have undone all of Creation, but was killed before he could utter the word.

Once reincarnated only years later in the 20th Century after the events of the first film, he simply would have been able to speak the name backwards and undo all of Creation, making the need for finding the stones irrelevant.