Here are two examples which come immediately to mind (all citations and page numbers are from the 30th Anniverary paperback edition):

In the opening scene at Connie's wedding (page 15),' Puzo writes about Don Corleone and his tuxedo:

"The guests so exclaimed at how well he looked in his tux that an inexperienced observer might easily have thought that the Don himself was the luck groom."

Then, just 30 pages later (page 45), in the scene describing Don Corleone's visit to the hospital with his sons to see the dying consigliere Genco, Puzo writes

"He (Dr. Kennedy) was surprised when his (Genco's) wife and daughters turned to the short heavy man dressed in an awkwardly fitting tuxedo."

Then Puzo writes about Michael's war injuries.

In the scene at Connie's wedding (page 17), he writes:

"When Michael Corleone was discharged early in 1945 to recover from a disabling wound...."

Then, writing about how Michael felt after killing Sollozzo and McCluskey (Pages 151-152), Puzo writes:

"The feeling was familiar and he remembered being taken off the beach of an island his Marine division had invaded. The battle had been still going on but he had received a slight wound and was being ferried back to a hospital ship."

There were others; We had an entire thread about them once, but I couldn't find it.