Apparently, nothing.

So what happens when a 10 year-old consumes a whole bottle of gummy CoQ10 and a whole bottle of gummy B-12 vitamins? Apparently, nothing.
When I discovered a red B-12 gummies on the floor of the kitchen, I was alerted to the fact that someone had apparently dropped it, en route to the living room, where Sam normally takes his supplements. When I found the second one, I was alarmed.
I looked for the bottle and didn't see it, so I took the two gummies to Sam and said "Where is the bottle?". He calmly said "Trash".
I immediately googled "B-12 overdose" and learned it's a water soluable vitamin and what overdose symptoms to look for. As close as we could surmise, it had been several hours since he had consumed them, with no adverse affects whatsoever. He had been to the playground. Had eaten dinner. And he was acting normally. Looked normal.
About a half an hour later, I realized the CoQ10 bottle was also missing. I tore through the trash and found both bottles, neatly recapped with their childproof caps, and discarded together. Empty.
Again, I rushed to the computer and googled "CoQ10 overdose". As far as I could tell, CoQ10 is an enzyme mainly used for heart conditions and there is no known overdose level. Watch for vomitting, diarrhea, etc. He was acting fine. Nothing so far.
Since the discovery, he has had potty time, taken a shower, played with his new electronic drum set, eaten a bowl of cereal, and is brushing teeth for bed. Nary one little sign that something is wrong.
I hesitate to call poison control or take him to the E.R. and I'll tell you why. When Seth was small, he took a swig from a bottle of ambesol. Following that, he had to have his stomach pumped and activated charcoal put in which made him vomit black tar all night long. Then, on another occasion, he drank Triaminic straight from the bottle. Poison control said he might be a little hyper from the sugar but otherwise fine. On a third occasion, he ate the moisture absorbing crystals from a suitcase while we were on a trip. It says right on the little bag DO NOT EAT. Poison control said they'd pass.
So I'm watching for signs of physical distress, pupil dialation, vomiting, or anything that might alert me that there's a problem. If there is, we are ready to hit the road. But I suspect those gummies are more sugar and gelatin than actual vitamins and enzymes. Of course I kept the bottles just in case. Not a chance I'm going to get any sleep tonight, though.
Thanks childproof caps for not doing your job. He was able to open both bottles??? Gimme a break!