Wa alaykum assalam wa rahmatullah wa barakatuh

 

In the Name of Allah, the All-Merciful, the Mercy-Giving

 

All praise is due to Allah. Peace and blessings be upon His Messenger Muhammad.

 

It is not clear what you mean by “accidentally name someone other than Allah during Salat.”

 

As for asking for Prophet Muhammad’s intercession, this may take either of two forms:

 

1- If one asks Allah, the Exalted, to allow Prophet Muhammad (peace and blessings be upon him) to intercede for him in the Hereafter, there is nothing wrong in that.

 

2- If one asks Prophet Muhammad (peace and blessings be upon him) to intercede for him with Allah Almighty to bring benefit or avert harm, this is prohibited. A group of scholars even considers this supplication a form of shirk, for a person here asks Prophet Muhammad for something he cannot do, since he is already dead. The Companions of Prophet Muhammad used to ask him to pray for them while he was alive; but never asked him to do that after his death.

 

Almighty Allah knows best.