What 'Residue overlap splice site' means?

Answer: 

Sometimes, in the peptide page of a gene you can see some residue in red, they correspond to "residue overlapping splice site".

This means that the three bases composing this amino acid are on both sides of a splice site: 1 or 2 bases are in an exon and the remaining base(s) are in the following exon.

Taking the AAEL008005 gene in A. aegypti as an example:

Peptide page: The "G" (pos.124) and the "K" (pos.216) are in red.

Looking at the bases coding for these two amino acids, on the transcript page: check that you have the "Exons, codons, translation, coding sequence" selected, as well as numbering the residues - at the bottom of the page. The three bases coding for the "G" are "GGT" - the first "G" belong to one exon (in blue) and the "GT" belong to the following exon (in black). The three bases coding for "K" are "AAA". The first two "As" belong to one exon (in blue) and the last "A" belong to the following one (ni black).

Admittedly, it's hard to see the difference in colour - but you can check on the Exon page for this gene, but then you don't see the amino acid sequence at the same time.