It depends a bit on the physical structure of the RAM, but for the most part, the errors fall on logically adjacent rows (i.e. nearby memory addresses) in the RAM. So most of the time, you'll only affect other RAM inside your sandbox, and if you affect something outside the sandbox, it won't be far outside.
I remember encountering a similar failure when designing a system; the particular memory controller and the particular DRAM module we were using both met all applicable specs, but when used together in a particular manner, they would fail miserably. The specific test was to alternate writing all zeros and all ones at different addresses. The RAM controller had an oddity where it would enable the drivers for the RAM data pins a very briefly before the data was known. For that particular data pattern, that meant that it would drive all ones on the data pins to the RAM for less than a nanosecond, before starting to drive all zeros (or the reverse). There's nothing really against that in the spec; the data was all correct for all the relevant setup and hold time requirements relative to the control signals. However, it caused a lot of noise on the ground plane of the DRAM module; we measured as much as 0.75V or so. (That's measuring the ground voltage on one side of the SO-DIMM to the ground voltage on the other side; it's shorted by a mostly-solid layer of copper, but that just wasn't enough to carry all the current with this particular access pattern.) So from the point of view of the RAM chips, it's a little like having your 2.5V supply voltage suddenly drop to 1.75V. It messes up all the reference voltages, so a 1 might be interpreted as a 0, or vice versa. The memory controller manufacturer refused to do anything about it (and it would've taken them many months to redesign and respin the chip anyway), but the RAM module manufacturer was friendly to us, and they beefed up the ground plane so that the noise level was much more manageable.
In any case, I'm sure there are thousands of faults like this that are just waiting to be found and exercised in any given system. No modern computer is 100% tested, they're far too complicated. There will always be some weird sequence of things that could happen and trigger some failure - but hopefully that sequence is so odd, it'll never happen.