To expand on a few of those items -
The backbox art is no longer a sure-fire way to tell a sample, as someone reproduced decals with that artwork, so anyone could re-decal their cabinet with the white doors up there at top.
The artwork differences on the playfield are one of the changes that is still unique - mainly because Mirco, when he reproduced his 'early' playfield (with the three magnets) wasn't aware that some of the art was changed as well. Specifically, in front of the main ramp - you'll notice the inserts are surrounded by a green rocket design - instead of white. Also, next to the autofire ramp (detail below), there's a post that was removed in productions games - sample games had the artwork rounded off for the post (regardless of whether the post was there or not.)
The autofire ramp & behind the UR flipper guide - originally this was two pieces - the ramp was mounted where it is now. But the metal guide on the left side of the ramp ended in a short postwith a rubber on it. Then another short ball guide mounted behind the flipper (same part # as the ball guide mounted to the right of the slot machine). They realized that having the autofire kicker ramp bordered by two rubber-wearing posts made it more difficult for the kicker to get balls up and around - so the ramp was changed to one piece - the left wall of the ramp comes down and ends down right above the rocket kicker. Funny enough, production manuals STILL show this as two parts. Check it out!
T-Nutted posts, at least in TZ, are difficult to keep tight. All the single short posts were routed on the underside of the playfield to accept T-Nuts. At some point, the posts were changed (longer threaded area) to accept nylon locknuts. This is another sure way to tell an early sample from a repro, as I'm pretty sure (not 100%) that Mirco's playfields don't have these either.
The "roof" plastic by the pop bumpers - you will note that there is one star post holding up this dual-layer plastic, and two metal posts. If you look in the manual - yes, even production ones - you will see that the star post, which is directly left of the bottom pop bumper, in the manual is moved out some - it is NOT up against the wood rail. You'll notice that the TOP plastic is also larger than the one under it, showing how the two used to be. On my playfield on the bottom side, there was a hole where this post should have been - it was filled in with a dowel and glued into place, then sanded down. As far as I can tell, this happened BEFORE the field went to printing - as I couldn't find any trace of seam on the top side. (And, unfortunately, I forgot to have HEP look for anything out of the ordinary when Chris restored my playfield.. so now, I'll never know.) I wouldn't be surprised if yours has a hole down there as well.
Oh - your Mini-Playfield likely won't have the spring / leveling feature. If it does, it was added later by an owner.
Your instruction card (it's a strange color.. Mine was white.) likely ends in "-1" instead of "-2". The only differences? A period was added, and font-size was enlarged. 
You SHOULD have a wiring harness for the top two door flashers - look for an unused 4-pin .156" header, with three wires going to it. That will plug into flasher board.
Your game was probably also sent with the left spiral sign. Mine was installed - the same tech that scraped off my 'GUM-Ball' insert and put the decal on the right spiral sign removed the left one, and left it in the cabinet. (Idiot me, long ago I figured I didn't need them. I threw away the mounting bracket, and then later, somehow lost my plastic. Argh.) You may find screw holes on the mini-playfield up where that mounted.
You will also have a plastic shield over the main ramp switch. (I do too..) This was changed and removed - to be replaced by a grey rubber booty.
The optos - the 'Clock Passage' opto just scores you some points. (During 9.4H testing, I had asked Ted if he could play a sound like when Camera was lit, or Town Square Madness was going - like when the ball comes out of Lock or is caught by the magnet. He declined, stating that it would go off far too much. After thinking about it, I agreed with that..) The 2nd Big Kick opto doesn't really do anything - though if it's blocked, the game will try to fire the autofire a few times, before giving up. Apparently - and I haven't found any confirmation of this, I don't think - there was an idea of using the autofire kicker as a second 'ball lock' area.
Oh, and in the backbox - you'll find your 8-driver PCB (the small one that's connected to the MPU via the 'Display' cable) is mounted on the left side of the backbox - instead of where they moved it in production games - the upper right.
Yes, I know far, far too much about sample/prototype/production differences. I had a webpage up that went over MUCH of this before Gameroom ran their article. Since I was working at the arcade when we took delivery of the Sample TZ, and then made it into my collection.. it'll never leave.
Centerport, NY
