Back in 1955, Doc Emmet Brown is spotted by his past self as he is working on the cable in the park, at which point, the latter asks the unrecognizable white-haired man to "be a pal and hand my five-eighths wrench" out of a toolbox, to which future Doc Brown replies "Five-eighths? Don't you mean three-quarters?", with his past self realizing the mistake, Why, you're right.
The whole scene seems to imply (to me at least) that future Doc, realizing that was the reason why the cable snapped 'back then', tried to be indeed a good pal and helped past Doc by giving him the proper wrench.
Now after rewatching the movie I realize, that the wrench was used to adjust a bolt that could arguably have no impact on the outcome of what is to come, so which one is right?
- The whole interaction is indeed harmless and will have no effect.
- He gave himself the right wrench, but that was indeed the reason why the cable snapped.
- He deliberately gave himself the wrong wrench passing it as good so that the cable would snap.
- Is this just a plot hole?
PS: I do realize the movies never claimed to be hard bend on getting things right or being proper Sci-Fy, but given how well thought of a lot of the stuff is (in terms of continuity) I'd like to know if there is something to the scene considering how the Doc was so adamant in avoiding interactions.