Factual error: In the scene, where Paul Smecker is checking the green trash-bin, he finds a bullet from Ivan Checkov's gun. Nevertheless, earlier (in the plot), or later (in subsequence of the scenes), in the scene, where Connor MacManus is falling down with toilet on Russians' backs, Ivan Checkov, while the toilet hits his bald head, is shooting with his gun, but he misses the trash-bin - the angle of shooting is obviously too extreme to hit the bin. (00:23:34)
Factual error: When the news reporter is at the Lakeview Lunch which is supposedly on Commonwealth Avenue in Boston, below her name it says South Boston, as if that's where they were reporting from. (01:04:10)
Factual error: At the beginning, the MacManus brothers are attending a Catholic mass. The priest is saying the Our Father, and concludes it with "For thine is the kingdom, the power, and the glory for ever and ever." However, Catholics do not include this line when they say this prayer - only Protestants say this. Also, the prayer is never said before the priest gives his homily as it is in the movie.
Factual error: When Papa Joe kills Rocco, his gun, which should have lots of kick, doesn't kick at all, yet this bullet which produced no kick at all knocks Rocco's chair over when it hits him.
Answer: The priest thought they were trying to attack or assault the other priest, but since they Saints are very religious and the other priest knows it, he let them be. They kissed the statue to show respect.
Toolio