Nettles black loop
1969 Topps - [Base] #99.1 - 1969 Rookie Stars - Danny Morris, Graig Nettles (Black Loop Above Twins) [Good to VG‑EX]
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1969 White Letters (group), including Rookie Stars and Mantle
Various checklist errors in the 60s: 1967 Tom/Dick Kelley, 1966 #101 Spahn/Henry, 1969 #107 Jim/John Purdin. Due to cards being printed in multiple series.
1983 Fleer fingers on back; weird printing error
1981 Fleer - [Base] #126.2 - Ron Cey (Finger on Back)
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Skip-numbering: considered an error? Made collectors think they were missing cards in the set to buy more packs intentionally, including some famous short prints.
1982 Fleer - [Base] #603.1 - Lee Smith (Upside Down Cubs Logo on Back)
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