Let's examine that model.
We have at the beginning a galactic cloud of gas and dust through which passes a large body (perhaps a star, brown dwarf, whatever ... something to disrupt). Now there is turbulence in the cloud of some degree upon which to "fix" the condensation of some new star.
In an eddy of that turbulence an area of higher that normal concentration of mass occurs which acts as the focus of further gravitational collapse. As matter is pulled in from outlying areas, rotation increases to conserve angular momentum.
We should note here that gravity is like a rubber band. What goes down the hole will come right back out of the hole ... IF ... nothing stops it. Without a collision, without something to break the velocity ... anything falling into a gravitational field will just come back out. The collision generates heat. The heat is radiated into space. The material is then "stuck". If you put all radiation in space back into the bodies it came from ... the whole thing would blow up and resume its original configuration. Hmmmm ... I take that back ... Most would go back out but some very hot bodies would remain held by gravity ... and black holes are'nt time reversable.This collapse, in addition to increased rotation, causes a compression of the cloud since it now takes up less space, vis. it's pulled in ... and ... down to the plane of rotation. One consequence of this compression is to put "folds" in the cloud similar to what you would get if you held your finger to a tablecloth and turned it.
These folds can generate "arms" as areas of compression and expansion develop in the folds where the material resists being compressed uniformly.
In addition to all this, the material as a general rule will follow a "corkscrew" path as it orbits the locus of gravitation (the proto-star). It does so because the orbital plane of the gas cloud cannot be a conic section. It must be a flat plane. Hence, there is a force accelerating gas not on the plane ... to the plane. And because there is nothing to stop that motion (except collision), the momentum of material arriving at the orbital plane will be non-zero and so it will continue again back out of the orbital plane in the opposite direction where again it will decelerate and once again be brought back to that plane. Therefore, it's path is sinosoidal.
In addition to this sinosoidal motion, the overall velocity relative to the backdrop of stars will be greater when it crosses the flat plane. It will therefore go to a slightly higher orbit ... and ... on the downturn ... slower velocity and lower orbit. The result is a corkscrew path.
In addition to this motion, we have the "prograde" rotation associated with the accretion process itself wherein lumps of material condense-coalesce to form "sub-nebula" (the proto-planets).
One other note
Gas and dust not immediately in the proper plane will be sandwiched between two conic sections. Consequently, the further you are from the star ... the greater is the size of your "accretion zone". This setup is countered by the fact that there is less mass involved in solar system formation at greater distances than nearby due to weakened gravity out there. Therefore, large planets form out past the Earth-size ones in general.
All in all, one can see with these complicated induced motions, there will be many collisions among the sub-nebula and thus the planets are formed.
And, of course, they form in a hierarchical fashion
When observing the moon it is easy to imagine that all of its collisions were with comets, asteroids, meteors, etc. of sizes no larger than, say, one ten-thousandth of the moon's mass. After all, just look at the sizes of its craters. But ... a really huge impact will leave no crater ... it will melt the crust and be "paved" over with fresh, hot material. You will not observe a round thingy ... it will be a smooth "lava sea".
In fact, wherever a planet size body is forming, there is probably another body of similar size forming in roughly the same orbit perhaps nearly on the other side of the sun. And several other near planet size and a host of smaller things. Get it? Few big ... some average ... many small.
If the very large other body is very far away, it will take a long time to work its way around to the primary big body. In fact this must be so since another big body could not form near a primary large body in the same orbit ... it would get "sucked up" before it got large.
So what we have here is my candidate for "Cause of Anamolies"
There are only a few basic options for what happens when the primary body finally gets "whacked" by the final accretion (or near final).
The trouble with other models
Collision models propose just that ... a collision. As such, they are incredibly unlikely given the small spatial displacement of a planet compared to the enormity of space surrounding them. If the Earth were a marble ... Mars would be a pea a hundred yards away. Certainly, bodies attract one another but if they have any angular momentum relative to one another ... they simply won't hit. They just take a turn around and nothing more. To insure a "hit" by an interstelar interloper you need many chances ... thousands of near collisions. However, if the bodies are in the same orbit to begin with, the chances of them meeting up sooner or later are all but inevitable.
Fission models for Lunar creation are impossible. If matter is stable in one body there is no known mechanism for "fizzing" them into two. If induced by a passing large body, you have the same problem as the above. If two bodies just "graze" one another ... that's not fission ... it's what I've beeen alluding to in all the above. And grazing models for the creation of the entire solar system have all but been abandoned for the above "collision" reason as well as recent discoveries of planetary systems around other stars making them appear common.
Exploded planet models cannot produce a mechanism for the explosion. To the best of my knowledge, matter in bulk does not escape a gravitational field in which it is caught except by means of the nuclear force (as in a supernova) ... or by some sort of black hole gravitational ejection. Perhaps a planet could be blown asunder by a uranium core gone critical ... but where to get such enormous quantities of that stuff and in a form pure enough to generate the requisite explosion? And a "phase change" (electromagnetic interaction) gives me the impression of ... at maximum ... generating a planetary "hrumph" and a ten foot drop in sea level. Blowing a planet apart in short time is an undertaking of tremendous energy and power. Since Mr. VanFlandern champions the exploded planet theory, I'll keep an open mind ... but I really need a plausible mechanism to remain interested in EPH instead of a simple breakup (regardless of indirect evidence for the former).