One example is the spell Hermione uses to set Snape's cloak on fire in Philosopher's Stone. It isn't named in the book (she used her bluebell flames with no known incantation) and it stands out because surely if she wants a random fire spell she should use Incendio (presumably named after the film was made) but she says 'Lacarnum Inflamari.'
According to an FAQ on JK Rowling's website, she commented:
"Some of the new incantations, such as ‘lacarnum inflamari’ must have sounded more dramatic onscreen – although by the time you’ve managed to say ‘lacarnum inflamari’, you’ve surely lost precious seconds in which the Devil’s Snare might have throttled you. But that’s showbiz."
A list of spells that appear only in films or games but not in the books has been compiled by The Harry Potter Lexicon here.
Alarte Ascendare (Lockhart vs Draco's snake)
Everte Statum (Draco's attack on Harry in the same scene)
Fera Verto (McGonagall, for some mad reason, turning animals into water goblets)