This issue has variants.
There is a variant of this comic included in the Knightsend Part One boxed pack that has the words "DC Universe" in the corner box rather than a bar code.
KnightsEnd crossover continued from Batman (DC, 1940 series) #509.
KnightsEnd corosover continues in Detective Comics (DC, 1937 series) #676.
Letters from Joey Marchese, Paul N. Hicks, Charles D. Brown, and Nick Richard.