Error list for
Peter Webb, Stratifications and Mackey functors I: functors for a single group,
Proc. London Math. Soc. (3) 82 (2001), 299-336.

Page 307 line 9 (third sentence of the proof of 2.5): It should read:
Assuming that $M_{i-1}\subseteq {\rm Im} f$,
In other words, the containment is the wrong way round.

Page 324 line -4 (statement of Theorem 9.1): It should read
$Hom(\Theta(\lambda),\Theta(\rho))=0$ unless $\lambda\ge\rho$.
(Clearly the strict inequality > makes no sense here.)