Rick Warren is being criticized in some circles for his overtly Christian invocation. I'm more concerned with his mathematical deficiencies.
At some point during his prayer, he references "America's peaceful transfer of power for the 44th time." (Leave aside for a moment the awkwardness of this phrase.)
While President Obama is indeed the 44th person to be inaugurated, there have been just 43 peaceful transfers of power: I'm sure neither the British nor our own Continental Army would have described the first transfer of power, culminating in George Washington's inauguration, as "peaceful."