Factual error: When Steve Carrell is standing-by to read his news bulletin, the Floor Manager cues him to begin by counting down from 5 seconds to zero. In reality, a Floor Manager only ever counts out loud the numbers 5 and 4, while 3, 2 and 1 are communicated via hand signals. This is to prevent the Floor Manager's voice being picked up on air when the presenter's mike is faded up. This error occurs in countless films.
Continuity mistake: There are two scenes in the movie where Grace is noted to have donated blood in the dialogue, one near the beginning, and one, the final scene. The blood donation is a fairly important turning point for Bruce's rehabilitation. And yet, neither of Grace's bare inner arms in either scene show any iodine, bruises, holes, or perhaps the easiest to spot, any small bandage that would result from blood donation.
Continuity mistake: In the scene where Bruce and God are standing on water, after God reaches into the water to get the beaded bracelet, he puts the bracelet on his wrist. However, just as God turns to walk away the bracelet is in God's hand, not on his wrist. As you see God walk away he's looking down and it seems as if God is just then putting the bracelet on his wrist. (00:35:55)
Other mistake: When Grace is running after her fight with Bruce, she sees trees on her right hand side with "Bruce + Grace" and then "forever and ever" inscribed on the following trees. However, when Grace looks to see how far back this is written on the trees, she leans to the left side of the screen (or her right). This wouldn't allow her to see farther down the street, since it was written on the trees to the right.