Here's a couple of items that, in hindsight, I would do a little differently:
1. Log lift hinge.
I used 5/8" hot roll solid round for the pins ... seems a little undersized to me now. Probably would have been better to use 3/4" or 1" pins and used some bosses on the brackets (which are 3/8" thick) or on the log lift frame tubes. The hinge and pins aren't really greasable at this point ... and I suspect they will probably wear pretty quick.
Another thing is the actual location of the log lift itself when it's raised - it's high and close enough to the beam that the push block will hit it if the push block cylinder is extended while the log lift is up. In fact, I've already managed to do that ... fortunately I was at least paying enough attention to stop it ... otherwise I would ripped the brackets completely off the beam. I could handle this pretty easily by trimming about an inch or so off the top of the log lift frame.
2. Fold-up table grate. By choosing to locate the bolts, which the table grate pivots on, at the very end of the table (nearest the splitter beam), the table grate cannot be folded up all the way when the log lift is in it's raised position. This could have been avoided by relocating the bolts which provide the pivot, a few inches further out towards the end of the beam.
3. Riser for the filler/vent cap on the reservoir. (This one is for CDN Farm Boy

) I used a small (1" tall) riser from Surplus Center that was pre-drilled for the filler vent cap and welded that directly to the reservoir. Yesterday when I set up to split, the splitter wasn't level, with the side of the of the reservoir with the filler/vent cap on the low side. During the first cycle of the push block cylinder, it promptly puked out that quart or so of fluid that I used to top off the reservoir.
Apparently I didn't leave quite enough airspace ...
Probably should have used some 3" pipe (which I actually have) to extend the riser up several inches.
4. Location of the suction strainer. I mounted this on the side of the reservoir ... and, as such, it sits up off the bottom of the reservoir by about an inch or so. Locating it on the bottom of the reservoir would have given me more usable drawdown capacity for the hydraulic fluid. Practically, I don't think is going to be a problem, but it could have been ... particularly if I had used a larger diameter or longer cylinder.
There are probably some other items but the above are a few that I came up with off the top of my head.