When Tom is taking Mr. Taylor home he tries to roll the window up and the handle breaks off before he can roll it up. In all subsequent scenes the window is completely up.
When the owl is flying through the house, it flies under 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.
When Tom and Paul were talking about house sitting, Paul referred to Lisa's real name, Tara.