I made the mistake of assuming a torte would be done when the timer went off. I removed it from the oven and turned off the heat. Forty minutes later I discovered my error. Is it safe to reheat the oven (sans-torte) and continue cooking from where I left off? Are there any risks to doing this generally in baking?
You haven't mentioned exactly what's in the torte, but I am assuming that the only potentially "unsafe" ingredient is eggs. Thus, the only possible danger is that the eggs might be undercooked, posing a very minuscule (considering that most egg yolks/whites aren't contaminated in the first place) risk of salmonella.
But we're talking about a torte here, which isn't going to be finished until the eggs are set, and the setting temperature of eggs isn't that far off from the salmonella-killing temperature (63° C vs. 74° C). Use a thermometer if you're concerned.
Of course, if you're using pasteurized eggs then they should be free of bacteria to begin with and you have nothing to worry about at all.
Most likely, the worst thing you have to worry about is the torte drying out a bit, since you'll be increasing your overall baking time to get it back up to temp.
Edit: With respect to quality of the finished product, I might worry with a regular (flour) cake, because increasing the total baking time gives it more time to develop gluten and dry out, but a torte has little to no starch, so you're not really in much danger there. Just keep an eye on it, make sure it doesn't burn, and you'll be fine.