During the final act of Bill & Ted's Excellent Adventure, the gnarly duo place traps and things needed in convenient locations for the boys to find to help get some historical figures out of jail. They just tell themselves "We'll have to remember to put this here in the past" or something.
IIRC, they movie ended and they gave the phone booth back to George Carlin Rufus. How did they place all those things for them to find if they never had the time machine anymore?
Serious answer: Rufus joins them for a jam at the end of the film, so they probably did it then.
Frivolous answer: it's time-travel dude! In theory, they could have gone back at any point in the future to set those traps (and remember that they got the time machine back again in the sequel and they do something similar at the end of that film).
Perhaps "in the future" means after time machines have been invented in their natural time stream. That is, they'll go about their lives until they are vastly famous musicians and time machines have been invented, and take care of these house-keepping details then.
There's no mention in the film (as far as I can remember) of returning the phone booth to Rufus. Therefore we assume that they were able to do everything afterwards.
Although, it could have been just 'done' as part of their other time travels and not shown to the viewers.
Since it was night time during the jam session with Rufus, it can be assumed that they did what they need to do, as far as placing the objects and personages of historical significance where they needed to be, during that time. Let's face it. Bill and Ted aren't the sharpest knives in the drawer. They probably have a bad short term memory...collectively.
