In the opening store robbery and subsequent firefight with the police, one of the officers is using a rifle to pick off the criminals. Each time he fires, the accompanying sound effect is that of a firearm that is equipped with a sound suppressor, when it's apparent none is attached to the end of the rifle's barrel.
When Maggie jumps back into the Mustang she tosses her purse into the back seat, but it bounces outside the car, the strap catching on the convertible frame. Later she reaches for her purse in the back seat.
When Maggie opens the box for the first time in the restaurant her pistol, Hammerli 280, is unloaded while Bob says "Its loaded". There is only one clip in the box. In the next cut there are two clips in the box and the pistol is in fact loaded.
Claudia buys cans of Progresso Ravioli in the store, and then serves that ravioli at dinner. One can easily see the areas of the ravioli that do not have sauce on them. The sauce is atop the ravioli, which clearly indicates that the ravioli was cooked separately and the sauce was placed over the pasta later. However, canned ravioli would have a completely different appearance; it would have sauce dispersed evenly all over each ravioli.
The goof items below may give away important plot points.
While escaping her last job with Victor the Cleaner, Maggie pulls the Mustang's emergency brake, locking the car's rear (drive) wheels which sends it spinning out of control. Later, while Maggie and the Cleaner are struggling underneath the car on the edge of the cliff, the car's rear wheels are spinning freely.
When Victor's car hangs off the cliff the rear wheels are off the ground spinning while both he and Nina are underneath. After the shot of Nina pressing Victor's arm into the rear tire the next shot shows the left front tire spinning in the dirt. Mustangs don't come with all wheel drive.
After putting in the password in the nuclear program on the computer near the ending, Maggie tries to copy over 75 megabytes of data onto a floppy disk. This would be impossible considering floppy disks of 1993 could only carry at most 2.88 megabytes of data.