The info on a court summons, if it actually gets this far, probably will be rather brief. It should have the name of the person or company who is suing you and perhaps will state that the law suit is about an unpaid debt. There likely will be a docket number and, probaby a court date and court room number and address of the county court that would hear the case. There also likely will be some standard routine instructions for that court attached..
I wouldn't think that there would be much more than that on the actual summons.
In most states (but, I don't know about MN), this one would not be heard in small claims court. You would have to utilize the discovery process before the court date to obtain the info that you want about this alleged pay day loan.
BTW, there is nothing preventing you from searching your own bank records to see if you did receive a $400 electronic deposit from somebody back in December of 2008. I am getting the impression that you have taken out pay day loans in the past. You just do not seem sure that you took out one from this particular place. I can't tell you how beneficial it is to regularly balance your checking account. Then you would not be in this position of trying to remember what you did ten months ago.