Both of these red pieces look like what we call “dust” - they’re smaller parts of the branch and contribute to the overall shape. Did you have a specific question about them?
Just wanted advice for future reference! Related, would this be one I just found be considered dust? #4356576 Thanks
Hi ieatleeves,
The red segment may certainly be a good trace. You’ve done an awesome job of finding what we call a “black spill” where the dye has bled over the lines and stained the inside of the neuron which makes it difficult to find the correct continuation of the branch.
Remember, review mode is how your trace compared against other player’s traces so it is possible to have a red segment actually be a good segment. Black spills are very tricky and it’s common for them to be missed, so I’m not surprised this showed up red in your review mode.
This cube ended up being part of a larger merger branch which has since been removed. Thus I can’t confirm if the red black spill segment continued correctly; hopefully we find the cell that this branch belongs to in the future! 
Best,
M.
Alrighty, good to know. Thanks!