In the beginning when they are measuring Buffalo's biggest cookie, the tape measure is clearly not measuring the middle (diameter) of the cookie. The measurement would only be accurate by the diameter size.
When Bruce is explaining to his dog where he should pee, he repeats, "House, bathroom, bathroom, house" and points to the house when he says house and to the outdoors when he says bathroom. In one shot, though, he points to the house and says bathroom and the outdoors and says house.
Bruce describes the Polish bakery in his news story as home of the "cream-filled Polski Pierogi". A pierogi is a meat or cheese dumpling, and would be sold at a deli or meat market, not a bakery - a paczki is a fruit or cream-filled fried pastry.
Grace talks about the AB+ blood type as if it's rare and high in demand. In reality, AB+ is the least in demand because AB+ can accept any other blood type. O- is the most in demand because it can be donated to any other blood type.
Throughout the film, Bruce is excited about his opportunity to finally have his own live shot. In reality, every reporter at a television station have numerous live shots every week. No television reporter considers them to be all that special.
When Bruce wants all prayers organized into files, file cabinets start filling up the room he is standing in. By the time the last cabinet is put in front of Bruce, the position of his head behind the cabinet changes.
When Bruce answers prayers at high speed (at the computer), he puts his coffee mug down on his left. When he answers all prayers "Yes", the mug has disappeared from his left, and he picks it up from his right.
At Niagara Falls, while talking to the owner of The Maid of the Mist, Bruce shakes his head, which makes his hair messy. The scene cuts to Grace. When it cuts back to Bruce, his hair is parted and neat.
At the end of the movie when Bruce is telling Sammy to pee outside near the tree, Sam appears to be digging a hole at the base of the tree. (The hole is clearly visible.) In the next scene when Bruce brings the flowered chair outside to train Sammy, the hole is gone (though the scene is thought to be just a moment later).
Seconds before the monkey comes out of the hood's butt, the hood on his left(viewer's left) with the blue jacket has a thin mustache and a small soul patch on his chin. After the monkey has come out, he has a full goatee when saying Bruce is 'El Diablo'.
When Bruce looks at himself in the mirror, Sam enters the room to pee on the couch. The shot changes to Bruce, then back to Sam. On the right side of the screen, you can see the hand of the dog trainer, pointing to where the dog should be looking.
When Bruce Nolan plays Clint Eastwood and a shot is fired from nowhere, he is shocked and parks the car in front a diner. Right when he (Bruce Nolan) parks his car and before he sees himself in the rear view mirror, in the side shot, there is a middle aged man standing near the pole wearing a hat, shirt and shorts, clearly a camera man.
When Bruce and God are talking standing on the water, God bends over and picks up the Rosary beads. You can see fishing line making a V-shaped line in the water going from the beads to the top of the frame.
When Bruce is typing answers to the prayer emails, the contents of the prayers do not match the subject lines. For example, one prayer that has "RE: New Car" in the subject line is actually a request to find a lost cat.
(at around 30 mins) As the file cabinet closes after God thumps it, the drawer closes, but oddly the files within don't move along, and the file "Doctor", for example, stays stationary along both shots.
When Bruce Nolan plays Clint Eastwood, and a shot is fired, the street where he is driving is clearly daytime, indicating its not evening but almost around 3 p.m to 4 p.m., but when he parks his car and gets out, the shadows and sun disappears, indicating its around 6 to 7p.m.
When Bruce arrives back at the warehouse to talk to God, who isn't there first, a shadow (not Bruce's) is clearly visible on a column in the second row. Most likely it's the shadow of Morgan Freeman hiding and waiting for his cue, because in the following shot, he appears right behind a column in the first row at the same height where the shadow was cast on the column in the second row.
The goof items below may give away important plot points.
At the end, when Grace is hugging Bruce in the hospital bed, and Bruce notices he has the beads in his hands, Grace's eyes open and she mouths inaudible words, but in the next shot, her eyes are closed again.
When Bruce and Grace are hugging in the hospital, God makes Grace's prayer beads appear in Bruce's hand, startling Bruce. Several seconds before this happens, the beads are clearly visible, sticking out below Bruce's right hand as he begins to hug Grace.
At the end of the film, Bruce is apparently going to donate blood. However, he has just come out of the hospital having had medical procedures and received the AB blood transfusion seen in the earlier scenes. Individuals who have been hospitalized recently, who have been in surgery recently and who have recently received blood are ineligible to donate blood themselves. The waiting period is 3 months.