Continuity mistake: When Happy and his Grandmother arrive at the nursing home, Happy puts his Grandmother's suitcase under the bed. In the next shot it's not there anymore. (00:09:45)
Other mistake: Near the end of the closing credits, when the Warner Bros. Copyright appears, you'll see the very first word "All" spelled incorrectly as "Al" in "All material is protected by Copyright Laws of the United States and other countries throughout the world." (01:26:40)