Joshua 21:10-11 has two unusual spellings.

ריאשנה is spelled מלא, the only place in תנ”ך where it is spelled this way.

קרית ארבע is referred to as אבי הענוק rather than אבי הענק as it is spelled earlier in Joshua 15:13.  The word ענק/ענקים occurs numerous  times in תנ”ך, but nowhere else is is spelled ענוק.