At this wiki
http://en.wikipedia.org/wiki/Capital_punishment_in_the_United_States
It says OK uses lethal injection primarily but it does have secondary methods.
The other methods according to this wiki are as follows.
http://en.wikipedia.org/wiki/Capital_punishment_in_Oklahoma
“However if lethal injection is to ever be outlawed the state has two secondary options outlined in its state constitution. The first being Electrocution by electric chair which was used before the national moratorium began in 1967, with shooting by firing squad as the second option should both lethal injection and electrocution be outlawed.”
LOL! Guess my initial reaction wasn't that farfetched afterall!
"Let's do it."
Last words of Gary Gilmore, January 17, 1977.