When Tom is taking Mr. Taylor home, he tries to roll up the window, but the handle breaks off before he can do this. In all subsequent scenes the window is completely up.
When the owl is flying through the house, it flies under the chandelier, but the chandelier came crashing down a few minutes earlier.
On the subway, Tom gets shot with a water gun by a little boy that appears from nowhere. The boy sits down, then disappears.
When the mice escape and are running across the floor, they do not look like live animals. They have no legs, only run in a straight line, and their tails don't move. They are obvious wind-up toys or something like that.
When Tom and Paul were talking about house sitting, Paul referred to Lisa by the actress' real name, Tara.