Doc goes off to intercept Marty Jr, and leaves Marty to do the rest. Marty Jr wakes up prematurely and interrupts the plan.... but what was Doc doing that whole time? He clearly wasn't monitoring Marty Jr (even though he suspected he didn't knock him out long enough) and he obviously wasn't watching over allyway-body Jennifer. Was he across the square at the Cafe 90s having a Splurge just hoping Marty came through?
shareHe went to pick Einstein up from a suspended animation kennel. Pay attention to the end of the original and the beginning of this. Einstein's not with Doc until Doc lands the Delorean after Marty buys the almanac.
shareThat checks out.
But it seems odd, doesn't it? Went through a lot of effort to backtrack this moment in time, and find a solution to this problem and come up with a plan. Rushes in to grab Marty to execute the plan. Goes to intercept Jr, and plan is now underway..... so what does he do?
"Well I guess I should go pick up my dog RIGHT NOW."
Well Robert Zemeckis and Bob Gale would agree about some of the criticisms of what unfolds in 2015. They admit they wrote themselves into a corner with how the original ended and never planned a sequel, so they had to contrive things a bit to get the plot moving just like leaving Jennifer in the alleyway so the police could take her because they wanted the character out of the way and to just focus on Marty and Doc.
That said, Doc not being completely logical still works because as clever as he is, he's still eccentric and a bit mad right from his opening scene in the original. He tries out the time machine at Twin Pines Mall. It's late but it's still a place where anyone could've witnessed it, and when he returns at the end of the film, he comes crashing into Marty's garden in broad daylight and then takes off where Marty's family or neighbors could've witnessed it, and indeed Biff did. He did all that despite the fact that there was no rush to go to the futureš