In this Wikipedia page the third covariant basis vector in the spherical coordinate system (when using the physics $r, \theta, \varphi$ convention) is:
$$ e_{\varphi} = R \cos \theta (-\sin \varphi \quad \cos \varphi \quad 0)$$
Is this wrong? In both this answer and Pavel Grinfeld's textbook (section 9.2.8) it appears that it should be $\sin \theta$ instead of $\cos \theta$.