When Luca and Lena meet, Lena's left hand jumps between shots multiple times.
As Miss Universe steps into the pool, her right arm can be seen reaching for the rail. In the next shot, however, her arm has moved away from the rail.
When the conductor comes on stage the violinists in the orchestra are using one hand to clap in their lap. The etiquette is slowly hitting the bow onto the partition support.
In the restaurant, when Caine tells Keitel that the old silent couple is mute, you can clearly see the mesh that holds Caine's wig in place on his right temple.
In a pool scene there is a discussion about left-handed people and the South American tells the group he is left-handed. However, earlier in the movie that character was signing autographs with his right hand.