For instance, Sen. McCain appeared before a giant photo of what his campaign apparently thought was Walter Reed Army Medical Center, site of a shocking exposé of poor living conditions for wounded veterans that subsequently turned into a cleanup effort/photo-op for Pres. Bush and the Republicans.

Unfortunately, the building shown in the massive picture is actually Walter Reed Middle School in North Hollywood, California. Oopsies. (TPM additionally notes that the building was used by West Wing too; a brilliantly subtle jab at Obama then? Doubtful...)
The bumblin', stumblin' Team Magoo have also taken to using the Heart song "Barracuda" at events but apparently forgot to ask the band's permission. Heart's decidedly Democratic members have since had a cease and desist notice issued to the McCain/Palin camp.
More examples of conservagaffes:

Tip o' the hat to all the emailers sending me more goofs.